Methods and apparatuses relating to telecommunications networks

Abstract

A method comprising receiving, at a session management function, SMF, of a telecommunications network, information indicative of charging characteristics for at least one user; and determining, at the

Description

Field This specification relates generally to telecommunications networks. 5 Background In modern telecommunications networks, a session management function (SMF) is able to transmit charging data to a charging function (CHF) of the telecommunications network which is used by the CHF for generating call detail records for users of the 10 telecommunications systems. Summary In a first aspect, this specification relates to a method comprising: receiving, at a session management function, SMF, of a telecommunications network, information 15 indicative of charging characteristics for a user; and determining, at the SMF to use a reduced charging data logging mode based on the information indicative of the charging characteristics to collect and log charging data associated with the one user; and collecting and logging . 20 In some examples, the method further comprises: transmitting, by the SMF the charging data to a charging function, CHF, of the telecommunications network for use in generating at least one call detail record, CDR, associated with the at least one user. In addition or alternatively, the information indicative of the charging characteristics for the at least one user may be received at the SMF from a charging function, CHF, of 25 the telecommunications network responsive to a charging request transmitted from the SMF to the CHF. In some examples, the information indicative of the charging characteristics for the at least one user is received at the SMF from a policy control function, PCF, of the 30 telecommunications network responsive to a charging characteristics information request transmitted from the SMF to the PCF. In some such examples, the charging characteristics information request is transmitted from the SMF to the PCF responsive to identification of a connection loss between the SMF and a charging function, CHF, of the telecommunications network. 35 In some examples, the charging data associated with the at least one user may comprise at least one of: a data session duration and an amount of data used by the at least one user. In addition or alternatively, the charging characteristics may include an unlimited network usage quota for a data session. In some examples, the method further 5 comprises: receiving, at the SMF, information indicative of further charging characteristics for the at least one user; and determining, at the SMF to use an increased charging data logging mode selected based on the received information indicative of the further charging characteristics for the at least one user, to collect and log further charging data associated with the at least one user, and collecting and 10 logging charging data associated with the at least one user. In some such examples, the further charging characteristics for the at least one user may include a limited network usage quota for a data session. In some examples, the charging characteristics for the at least one user may include at least one of: a time limit for a data session, a data volume limit for a data session, and a change condition for a data session. 15 In a second aspect, this specification relates to a method comprising: transmitting, from a charging function, CHF, of a telecommunications network to a session management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of 20 the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging charging data associated with the at least one user. In some examples, the information indicative of the charging characteristics for the at least one user is transmitted responsive to receiving, at the CHF, a charging request transmitted the SMF. In addition or alternatively, the method may further comprise: 25 receiving, at the CHF, charging data associated with the at least one user, the charging data having been collected and logged at the SMF using the reduced charging data logging mode selected based on the information indicative of the charging characteristics; and generating, at the CHF based on the received collected and logged charging data, at least one call detail record, CDR, associated with the at least one user. 30 In a third aspect, this specification relates to a method comprising: transmitting, from a policy control function, PCF, of a telecommunications network to a session management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of 35 the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging charging data associated with the at least one user. In some examples, the information indicative of the charging characteristics for the at least one user is transmitted to the SMF responsive to a receiving, at the PCF, a charging characteristics information request transmitted from the SMF. In some such examples, the charging characteristics information request comprises a session 5 management, SM, policy association modification request. In a fourth aspect, this specification relates to an apparatus comprising: means for receiving, at a session management function, SMF, of a telecommunications network, information indicative of charging characteristics for at least one user; and means for 10 determining, at the SMF to use a reduced charging data logging mode selected based on the received information indicative of the charging characteristics, to collect and log charging data associated with the at least one user; and collecting and logging charging data. 15 In some examples, the apparatus further comprises: means for transmitting the charging data to a charging function, CHF, of the telecommunications network for use in generating at least one call detail record, CDR, associated with the at least one user. In addition or alternatively, the information indicative of the charging characteristics for the at least one user may be received at the SMF from a charging function, CHF, of 20 the telecommunications network responsive to a charging request transmitted from the SMF to the CHF. In some examples, the information indicative of the charging characteristics for the at least one user is received at the SMF from a policy control function, PCF, of the 25 telecommunications network responsive to a charging characteristics information request transmitted from the SMF to the PCF. In some such examples, the charging characteristics information request is transmitted from the SMF to the PCF responsive to identification of a connection loss between the SMF and a charging function, CHF, of the telecommunications network. 30 In some examples, the charging data associated with the at least one user may comprise at least one of: a data session duration and an amount of data used by the at least one user. In addition or alternatively, the charging characteristics may include an unlimited network usage quota for a data session. In some examples, the apparatus further 35 comprises: means for receiving, at the SMF, information indicative of further charging characteristics for the at least one user; and means for determining, at the SMF to use an increased charging data logging mode selected based on the received information indicative of the further charging characteristics for the at least one user, to collect and log further charging data associated with the at least one user, and collecting and logging further charging data. In some such examples, the further charging 5 characteristics for the at least one user may include a limited network usage quota for a data session. In some examples, the charging characteristics for the at least one user may include at least one of: a time limit for a data session, a data volume limit for a data session, and a change condition for a data session. 10 In a fifth aspect, this specification relates to an apparatus comprising: means for transmitting, from a charging function, CHF, of a telecommunications network to a session management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging 15 mode for collecting and logging charging data associated with the at least one user. In some examples, the information indicative of the charging characteristics for the at least one user is transmitted responsive to receiving, at the CHF, a charging request transmitted the SMF. In addition or alternatively, the apparatus may further comprise: means for receiving, at the CHF, charging data associated with the at least one user, the 20 charging data having been processed at the SMF using the reduced charging data logging mode selected based on the information indicative of the charging characteristics; and means for generating, at the CHF based on the received processed charging data, at least one call detail record, CDR, associated with the at least one user. 25 In a sixth aspect, this specification relates to an apparatus comprising: means for transmitting, from a policy control function, PCF, of a telecommunications network to a session management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging 30 mode for collecting and logging charging data associated with the at least one user. In some examples, the information indicative of the charging characteristics for the at least one user is transmitted to the SMF responsive to a receiving, at the PCF, a charging characteristics information request transmitted from the SMF. In some such examples, the charging characteristics information request comprises a session 35 management, SM, policy association modification request. In a seventh aspect, this specification relates to an apparatus comprising at least one processor and at least one memory storing instructions for a session management function, SMF, of a telecommunications network, wherein the instructions when executed by the at least one processor, cause the apparatus to perform: receiving, at a 5 information indicative of charging characteristics for at least one user; and determining, at the SMF to use a reduced charging data logging mode selected based on the received information indicative of the charging characteristics, to collect and log charging data associated with the at least one user; and collecting and logging the charging data. 10 In some examples, the instructions, when executed by the at least one processor, may cause the apparatus at least to perform transmitting the charging data to a charging function, CHF, of the telecommunications network for use in generating at least one call detail record, CDR, associated with the at least one user. In addition or 15 alternatively, the information indicative of the charging characteristics for the at least one user may be received at the SMF from a charging function, CHF, of the telecommunications network responsive to a charging request transmitted from the SMF to the CHF. 20 In some examples, the information indicative of the charging characteristics for the at least one user is received at the SMF from a policy control function, PCF, of the telecommunications network responsive to a charging characteristics information request transmitted from the SMF to the PCF. In some such examples, the charging characteristics information request is transmitted from the SMF to the PCF responsive 25 to identification of a connection loss between the SMF and a charging function, CHF, of the telecommunications network. In some examples, the charging data associated with the at least one user may comprise at least one of: a data session duration and an amount of data used by the at least one 30 user. In addition or alternatively, the charging characteristics may include an unlimited network usage quota for a data session. In some examples, the instructions, when executed by the at least one processor, may cause the apparatus at least to perform receiving, at the SMF, information indicative of further charging characteristics for the at least one user; and determining, at the SMF to use an increased charging data 35 logging mode selected based on the received information indicative of the further charging characteristics for the at least one user, to collect and log further charging data associated with the at least one user, and collecting and logging the further charging data. In some such examples, the further charging characteristics for the at least one user may include a limited network usage quota for a data session. In some examples, the charging characteristics for the at least one user may include at least one of: a time 5 limit for a data session, a data volume limit for a data session, and a change condition for a data session. In an eighth aspect, this specification relates to an apparatus comprising at least one processor and at least one memory storing instructions for a charging function, CHF, of 10 a telecommunications network, wherein the instructions when executed by the at least one processor, cause the apparatus to perform: transmitting, to a session management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for 15 collecting and logging charging data associated with the at least one user. In some examples, the information indicative of the charging characteristics for the at least one user is transmitted responsive to receiving, at the CHF, a charging request transmitted the SMF. In addition or alternatively, the instructions, when executed by the at least one processor, may cause the apparatus at least to perform: receiving the charging data 20 having been collected and logged at the SMF using the reduced charging data logging mode selected based on the information indicative of the charging characteristics; and generating, at the CHF based on the received recevied charging data, at least one call detail record, CDR, associated with the at least one user. 25 In a ninth aspect, this specification relates to an apparatus comprising at least one processor and at least one memory storing instructions for a policy control function, PCF, of a telecommunications network, wherein the instructinos when executed by the at least one processor, cause the apparatus to perform: transmitting, from to a session management function, SMF, of the telecommunications network, information 30 indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging charging data associated with the at least one user. In some examples, the information indicative of the charging characteristics for the at least one user is transmitted to the SMF responsive to a receiving, a charging 35 characteristics information request transmitted from the SMF. In some such examples, the charging characteristics information request comprises a session management, SM, policy association modification request. In a tenth aspect, this specification relates to a non-transitory computer readable 5 medium comprising program instructions stored thereon for performing at least any of the operations described above with reference to the first to ninth aspects. Brief Description of the Figs. For a better understanding of the present application, reference will now be made by 10 way of example to the accompanying drawings in which: Figs. 1A and 1B are examples illustrating various aspects of a telecommunications network; Figs. 2,3 and 4 are example message flow sequences; Figs. 5, 6 and 7 are flowcharts illustrating various operations which maybe performed 15 in accordance with examples described herein; Fig. 8 is a schematic illustration of a computing device which may be configured to perform various operations described with reference to Figs 1 to 7; and Fig. 9 is an illustration of a computer-readable medium upon which computer-readable code may be stored. 20 Detailed Description In the description and drawings below, like reference numerals refer to like elements throughout. 25 Fig. 1A depicts various aspects of a telecommunications network. In particular, Fig. 1A depicts a user equipment (UE) 101 in communication with an access network 102 (e.g. a radio access network, RAN). The access network 102 is further depicted in communication with a core network (CN) 103, which may include a plurality of network functions 104, and a data network (DN) 105. 30 Further aspects of the telecommunications network are depicted in Fig. 1B. In particular, Fig. 1B depicts the CN 103 that includes various network functions, NFs, including a session management function (SMF) 100 in communication with a charging function (CHF) 110. The CHF 110 is further depicted in communication with a unified 35 data management (UDM) function 120 of the telecommunications network. As mentioned above, the SMF is able to transmit charging data to the CHF. In particular, the SMF may process charging data for transmission to the CHF (e.g. at regular intervals). The processed charging data may be for use by the CHF in generating at least one call detail record (CDR) associated with the at least one user. 5 A CDR, also referred to as a ‘charging detail record’, may comprise a formatted collection of information about a chargeable event (e.g. time of call set-up, duration of the call, amount of data transferred, etc) for use in billing and accounting. In some examples, a separate CDR maybe generated for each party involved in a call. Moreover, 10 for a chargeable event of long duration (e.g. streaming a film over several hours), multiple CDRs may be generated. For instance, the charging data processed by SMF too may comprise network usage data for a data session (e.g. a protocol data unit, PDU, session) providing connectivity 15 between a UE 101 and a specific data network 105. Such data may include, but is not limited to, a volume of data used by the UE during the data session and / or a duration of the data session. In the event of a loss of connectivity between the SMF and the CHF, a log of charging 20 data may be stored locally at the SMF for transmission to the CHF once connectivity is restored. For instance, connectivity may be said to be lost between SMF 100 and CHF 110 when SMF 100 is unable to transit a request (e.g. a charging update request) to CHF 110. Once the connection between SMF 100 and CHF 110 has been restored, the log of charging data may be transmitted to CHF 110 for use in generating the CDR. 25 Put another way, subsequent to identification of a connection loss between SMF 100 and CHF 110, SMF 100 processes charging data (e.g., but not limited to, network usage data for the at least one user) associated with the at least one user. The collected and logged charging data is stored / buffered at SMF 100 and may be subsequently 30 transmitted to CHF 110. In some examples, once the connection between SMF 100 and CHF 110 has been restored, CHF 110 may fetch the collected and logged charging data from SMF 100 (e.g. via a network protocol such as SFTP) and use it to generate at least one CDR associated with the user. 35 However, collecting, logging, and reporting charging data for a complete data session may be unnecessary for certain user charging characteristics, leading to wasted computational resources at the SMF-side and excessive bandwidth utilisation for the connection between the SMF and the CHF. For instance, if the user’s charging characteristics are indicative of a charging plan which comprises an unlimited network usage quota for a data session (i.e. the user has an unlimited data plan), full CHF-side 5 charging collecting and logging is unnecessary and so less information is required at the CHF-side to generate the CDR than in the limited data plan case. In this way, transmitting complete logs of network usage during the session may constitute an inefficient use of network resources. 10 Put another way, it is not necessary for the SMF to generate and / or store logs for transmission to the CHF if those logs are associated with an unlimited data plan. Instead, in such examples, it may be sufficient to provide the CHF with details of data usage (e.g. usage units) and session duration so that policy counters can be updated by the CHF and / or a CDR can be generated to mark the usage according to the charging 15 plan. However, during a data session (e.g. a protocol data unit, PDU, session), CHF does not share plan information with the SMF, so it is not possible to make a determination at the SMF-side as to whether or not charging data logs should be processed and stored in full. 20 Implementations of the technology described herein relate to receiving, at a session management function, SMF, of a telecommunications network, information indicative of charging characteristics for at least one user; and determining, at the SMF to use a reduced charging data logging mode selected based on the received information indicative of the charging characteristics, to collect and log charging data associated 25 with the at least one user, and collecting and logging the charging data associated with the at least one user (e.g., using the reduced charging data logging mode). Other implementations of the technology described herein relate to transmitting, from a charging function, CHF, of a telecommunications network to a session management function, SMF, of the telecommunications network, information indicative of charging 30 characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging charging data associated with the at least one user. Yet other implementations of the technology described herein relate to transmitting, from a policy control function, PCF, of a telecommunications network to a session 35 management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging charging data associated with the at least one user. Various implementations of the technology described herein may increase network 5 efficiency when collecting and logging user charging data by reducing both networkside processing (e.g. at SMF100 and / or CHF no) and bandwidth utilisation (e.g. between SMF too and CHF no) within the network. For instance, since unlimited charging plans typically last for hours or days at a time, vast amounts of network bandwidth and / or processing may be saved by reporting consolidated charging data at 10 the end of the data session, thus abrogating the need to process multiple update requests during this period. Put another way, the CDR stream from the SMF to the CHF may benefit from lower utilisation. Various implementations of the technology of the technology described herein may be particularly advantageous in the event of a loss of connectivity between SMF too and CHF no. For instance, by collecting, logging, and 15 storing less charging data associated with charging plans that do not require detailed reporting (e.g. unlimited data plans), storage space at both the SMF-side and the CHF-side may be utilised more effectively. Various methods and apparatuses are described in detail below, byway of example 20 only, in the context of a telecommunications network, such as an Evolved Universal Terrestrial Radio Access (E-UTRA) network or a 5G network. However, it will be appreciated that the techniques may be applicable with telecommunications networks of other types (e.g. but not limited to other types of cellular network). 25 Although by no means limited to such an implementation, the examples of the technology described herein may readily be integrated into any new radio (NR) system which supports Converged / Convergent Charging as standardised in TS 32.290,3GPP release 15 (i.e. within a Converged Charging System, CCS). In particular, various aspects of the technology described herein may be applicable to charging sessions 30 initiated in both ‘blocking mode’, in which service delivery does not start until authorised by the CHF, and ‘non-blocking mode’, in which service delivery may start before / without authorisation by the CHF (e.g. responsive to transmitting a charging request to the CHF, but before receiving a reply at the SMF). It will be further appreciated that various implementations of the technology described herein may also 35 be applied in the context of an Online Charging System (OCS). As will be appreciated, SMF 100, CHF no and UDM 130 are core network (CN) functions in a telecommunications network. It will be further appreciated that such core network functions 104 may be logical’ rather than ‘physical’ entities, and so may be deployed in a distributed, ‘cloud-native’ manner. Put in other terms, the SMF, CHF 5 and UDM may be executed across one or more computing devices (such as the computing device described with reference to Fig. 8), which maybe physically remote from one another. Put yet another way, these network functions of the telecommunications network may be disaggregated. 10 A number of network functions are depicted, by way of example only, in Fig. 1B. In this example, network functions depicted within the dashed box are included in the core network 103. However, it will of course be appreciated that one or more of the network functions that are depicted as being within CN 103 may, in some examples, be located outside of the network core. In addition or alternatively, various network functions 15 depicted outside of the core network may, in some examples, be located within CN 103. As depicted in Fig. 1B, the core network functions 104 of a telecommunications network may include any combination of the following: network slice selection function (NSSF), network exposure function (NEF), network repository function (NRF), policy control 20 function (PCF), unified data management (UDM), authentication server function (AUSF), access and mobility management function (AMF), and session management function (SMF). Whilst depicted outside of the CN in Fig. 1B, in some examples, the application function (AF) maybe internal to the core network 103. In Fig. 1B, interfaces between network elements are prefixed with the letter ‘N’. For instance, the interface 25 between the UE and the AMF is labelled ‘Ni’, whilst the ‘Nudm’ interface allows the UDM to provide service to SMF 100, CHF 110 and the other network functions of the telecommunications network. Whilst only one base station is depicted in Fig. 1A, telecommunications networks may 30 comprise multiple base stations, sometimes referred to as transmit-receive points (TRPs) or access points (e.g. but not limited to gNBs and / or eNBs). A radio access network (RAN, NG-RAN) 102 may typically comprise thousands of such base stations which are in communication with one another and the core network 103. Together, the base stations may provide cellular network coverage to one or more terminal devices 35 101 (e.g. user equipment, UE, devices, such as mobile telephones) over a wide geographical area. In the example of Fig. 1B, SMF 100 receives information indicative of charging characteristics (e.g. charging plan information) for at least one user. SMF 100 processes charging data associated with the at least one user using a reduced charging data 5 logging mode selected based on the received information indicative of the charging plan. In some examples, SMF 100 may transmit the collected and logged charging data to CHF no for use in generating at least one CDR associated with the at least one user. In examples in which a connection loss between SMF loo and CHF no occurs, the io collected and logged charging data may be transmitted to the CHF responsive to determination that a connection between SMF loo and CHF no has been reestablished. It will be appreciated that, in some examples in which the CHF includes a plurality of CHF instances (the ‘CHF set’), the re-established connection between the SMF and the CHF may utilise a different CHF instance than was utilised prior to the 15 loss of connectivity. In some examples, the information indicative of the charging characteristics for the at least one user is received at the SMF from the CHF responsive to a charging request transmitted from the SMF to the CHF. In other examples, the information indicative of 20 the charging characteristics for the at least one user is received at the SMF from a policy control function, PCF, of the telecommunications network responsive to a charging characteristics information request transmitted from the SMF to the PCF. For instance, the charging characteristics information request may be transmitted from the SMF to the PCF responsive to identification of a loss of connectivity between the SMF and the 25 CHF. Alternatively, the charging characteristics information request may be transmitted responsive to a determination that a charging request transmitted from the SMF to the CHF has been lost in transit or has not been replied to by the CHF (e.g. before a timeout has been reached). 30 Put another way, in the event of a communication loss between the SMF and the CHF, there are two cases to consider. In the first case, the connection loss between the SMF and CHF occurs after a response to a charging request is received at the SMF from the CHF. In the second case, the connection loss between the SMF and CHF occurs without a response to the charging request being successfully received at the SMF from the CHF 35 (e.g. because the request or the response is lost in transit or has not been transmitted when connectivity is lost). The first case is described below with reference to Fig. 2, whilst the second case is described below with reference to Fig. 3. In some examples, the SMF receives information indicative of further charging 5 characteristics (i.e. another charging plan) for the at least one user and processes further charging data associated with the at least one user using an increased charging data logging mode which is selected based on the received information indicative of the further charging characteristics for the at least one user. For instance, the further charging characteristics may include a limited network usage quota for a data session. 10 Put another way, the SMF may identify that a Tariff Time Change (TTC) has occurred. Responsive to identifying the TTC, SMF may collect and log user charging data in a different mode to the one used for collecting and logging charging data prior to the TTC. For instance, when moving from an unlimited data plan to a limited data plan, the SMF may switch from a reduced charge data logging mode (e.g. in which only basic 15 usage data and session length is recorded / sent to CHF) to an increased charging data logging mode selected based on the charging characteristics associated with the limited data plan. Correspondingly, when moving from the limited data plan to the unlimited plan, the SMF may switch from the increased charge data logging mode to the reduced charge data logging mode. 20 Examples in which the SMF switches from one charging data logging mode to another as a result of receiving further charging characteristics for the user are described below with reference to Fig. 4. 25 It will be appreciated that the at least one user with which the charging characteristics are associated may correspond to one or a plurality of terminal devices (i.e. user equipment, UE). Whilst such devices (e.g. smartphones, wearable devices) may be operated by a ‘human user’, this is not necessarily the case. In some examples, charging characteristics may be associated with non-human-user-operated devices such as 30 remote sensors, autonomous vehicles and / or other devices. Fig. 2 is a message flow sequence, indicated generally by the reference numeral 2, in accordance with some aspects of the described technology. The message flow sequence 2 shows an example implementation within which aspects of a process, such as that 35 described with reference to Fig. 1, may be performed. The message flow sequence 2 shows a signalling procedure between a SMF and a CHF of a telecommunications network. The SMF and CHF may, for example, be SMF 100 and CHF 110 described above with reference to Fig. 1. 5 In general terms, this message flow sequence relates to the situation in which information indicative of charging characteristics for at least one user is received at the SMF from the CHF responsive to a charging request transmitted from the SMF to the CHF. In particular, as mentioned above, the examples described with reference to Fig. 2 maybe applicable to both blocking and non-blocking modes of operation for the 10 charging session. In operation 201, the SMF transmits a charging request to the CHF. For instance, the charging request maybe transmitted by a Charging Trigger Function (CTF) included in the CHF (e.g. CTF 101 in Fig. 1A). The charging request may comprise a 15 “NCHF ConvergentCharging Create” request as described in 3GPP TS 32.290. As described above, in the non-blocking mode of operation, SMF may start service delivery to the at least one user responsive to transmitting the charging request, without waiting for a response from the CHF (e.g. at operation 202). In some examples, the charging request may include a requested data quota and / or a notification Uniform Resource 20 Identifier, URI, for a “NCHF_ConvergedCharging_Notify” service operation in the request body. In operation 202, the CHF transmits information indicative of a charging characteristics for the at least one user to the SMF. For instance, the information may 25 be included in a “NCHF_ConvergentChargmg_create” response transmitted by the CHF and received by the SMF. The information indicative of the charging characteristics is for use in selecting a reduced charging data logging mode for collecting and logging charging data associated with the at least one user. Collecting charging data may collecting network usage data for a data session for the at least one 30 user and processing the network usage data to generate charging data for the at least one user and then logging the generated charging data. Examples of charging data that may be collected is described in TS 32.255 of the 3GPP standard for NR. In some examples, the charging characteristics for the at least one user may include at least one of: a time limit for a data session for the at least one user, a data volume limit 35 for a data session for the at least one user, and a change condition for a data session for the at least one user. In addition or alternatively, and as described above, the information indicative of the charging characteristics for the least one user may explicitly identify the reduced charging data logging mode. For instance, the information indicative of the charging plan may include a flag which identifies whether a reduced charging data logging mode is to be used by the SMF for collecting and 5 logging charging data for the data session for the at least one user. For instance, such a flag may indicate that the SMF should only log and report basic charging information such as session duration of the data session of the user or usage counts to the CHF. In such examples, the flag may comprise an information element (IE) “ReportOnlyUsageCoimt” which may take the values TRUE or FALSE. 10 In some examples, the response received at the SMF from the CHF includes details of the network charging resource(s) created for the data session for the user. For instance, the response may include a location of the created resource (e.g. a Uniform Resource Identifier, URI, which maybe included in the header of the response) and / or an 15 allocated quota for the created resource, which may be included in the body of the response. The SMF (or the CTF included in the SMF) may use the information included in the response to the charging request when sending at least one subsequent request (e.g. a charging update request) to the CHF for the same PDU session. For instance, the location of the created resource (e.g. the URI) may be included in such subsequent 20 requests. Based on the information received from the CHF at operation 202, the SMF may determine a type of charging plan for the at least one user. For instance, the SMF may determine whether or not the charging plan comprises a limited or unlimited network 25 usage quota for a data session for the at least one usre. As will be appreciated, when in the blocking mode of operation, SMF may start service delivery to the at least one user responsive to receiving the response to the charging request from the CHF. In operation 203, a connection loss between the SMF and the CHF occurs. For instance, 30 the connection loss may be identified at the SMF at least one message transmitted from the SMF to the CHF is not acknowledged or responded to within a threshold duration of time. Put another way, SMF may identify a loss of connectivity with the CHF based on a timeout of a request transmitted to the CHF. In some examples, the frequency with which connectivity status is monitored by the SMF may depend on the frequency with 35 which processed charging data is transmitted to the CHF. In operation 204, using a reduced charging data logging mode selected based on the information received from the CHF in operation 202, the SMF collecting and logging charging data associated with the at least one user. In some examples, the collecting and logging of charging data associated with the at least one user comprises at least one 5 of: a data session (e.g. PDU session) duration (e.g., a time interval from establishment of the data session for the at least one user to release of the data session for the at least one user) and an amount of data used by the at least one user during the data session. Since connectivity has been lost with the CHF, no update request is transmitted to the CHF. 10 In some examples, such as those in which the information received from the CHF is indicative of an unlimited data plan, the SMF may update a database (e.g. a local database) with usage data processed using the reduced charging data logging mode. For instance, the database may be updated with basic usage data such as call start time(s) 15 and / or end time(s), allowing for generation of a CDR specific to the unlimited plan. In addition or alternatively, the SMF may log usage count information for use by the CHF in generating at least one CDR, updating at least one policy counter and / or deciding on a QoS policy for the at least one user (e.g. whether / to what extent service should be upgraded or degraded for the at least one use). For instance, if a subscription plan 20 associated with a user is updated (e.g. because a new plan was purchased or an existing plan was renewed), the UDM may update the network with this information. In particular, if a data session (e.g. PDU session) for the at least one user is in progress, the charging characteristics of the new plan maybe provided to the SMF, triggering a session modification procedure (e.g. resulting in a different charging data logging mode 25 being used by the SMF). Further details on PDU session modification may be found in 3GPP TS 32.255, clause 5.2.2.2.3. In operation 205, a connection between the SMF and the CHF is re-established. In some examples, the CHF may comprise a plurality of CHF instances. In such examples, 30 prior to the disconnection in operation 203, the SMF may be connected to a first CHF instance of the plurality of CHF instances but may re-establish a connection with the CHF in operation 205 via a second CHF instance of the plurality of CHF instances. In other examples, the SMF may re-establish connection via the same CHF instance as before the disconnection. 35 In operation 206, the SMF transmits the logged charging data to the CHF (e.g. by including the collected and logged charging data in charging release request). Put another way, the SMF may terminate the data session by transmitting (e.g. via the CTF of the SMF) a “Nchf^ConvergedCharging^Release” request to the CHF. In some 5 examples, the collected and logged charging data may be transmitted to the CHF along with an indication (e.g. a flag) that the data has been processed using a reduced charge data logging mode and hence that the generation of the CDR at the CHF should be adapted. For instance, it may be indicated that an ‘unlimited plan-specific’ CDR should be generated based on the collected and logged charging data without performing any 10 further processing of the collected and logged charging data. It may be further indicated that the CDR should be released. In order that a policy counter maybe updated, the service unit that was last used in the data session may also be transmitted to the CHF. In some examples, operation 206 may occur responsive to determining that the connection between the SMF and CHF has been re-established. In other examples, 15 such as those in which no connection loss between the SMF and CHF occurs, operation 206 occurs at the end of the data session (e.g., when the data session is released). In operation 207, the CHF generates a call detail record (CDR) using the collected and logged charging data received from the SMF. As described above, in some examples, 20 the collected and logged charging data may be used to update a policy counter associated with the at least one user. As will be appreciated, various types of policy counter may be used to monitor different aspects of network usage. In some examples, the SMF triggers a “NPCF_SMPolicyControl_Create” operation 25 and / or changes the status of policy counters at the CHF. For instance, if updating a policy counter indicated that a monthly data limit (e.g. 1GB) for a given UE has been reached, the CHF notifies the PCF associated with the UE. In this case, the PCF downgrades the UE-Aggregate Maximum Bit Rate (AMBR) or / and UE Slice-MBR (e.g. until further notice). On the other hand, if the credit associated with the UE is topped 30 up (e.g. via a web portal), the CHF notifies the PCF. Responsive to this, the PCF may upgrade UE-AMBR or / and UE Slice-MBR (e.g. until further notice). Put another way, in some examples, the SMF may determine that Policy Charging and Control (PCC) authorisation is required. In such cases, the SMF may transmit a request 35 to establish an SM Policy Association with the PCF. For instance, the request to establish an SM Policy Association with PCF maybe transmitted by invoking the “NPCF_SMPolicyControl_Create” service operation. In some examples, one or more of the following may be included in the request to establish an SM Policy Association with the PCF transmitted to the PCF: a Subscription Permanent Identifier (SUPI), an identifier of a PDU session (PDU Session ID), a type of PDU session (PDU Session 5 Type), an identifier of a network slice (e.g., a Single Network Slice Selection Assistance information (S-NSSAI) of the network slice), a Network Slice Instance Identifier (NSI ID) (if available), Data Network Name (DNN), DNN Selection Mode, Generic Public Subscription Identifier (GPSI) (if available), Access Type, Radio Access Technology (RAT) Type, Access and Mobility Management Function (AMF) instance identifier and 10 if available, the IPv4 address and / or IPv6 network prefix, Permanent Equipment Identifier (PEI), User Location Information, UE Time Zone, Serving Network (Public Land Mobile Network (PLMN) ID, or PLMN ID and NID, see clause 5.34 of 3GPP TS 23.501), Charging Characteristics, Session AMBR, default QoS information, Trace Requirements, and Internal Group Identifier (see 3GPP TS 23.501, clause 5.9.7). 15 Fig. 3 is a message flow sequence, indicated generally by the reference numeral 3, in accordance with some aspects of the described technology. The message flow sequence 3 shows an example implementation within which aspects of a process, such as that described with reference to Fig. 1, may be performed. The message flow sequence 3 20 shows a signalling procedure between a SMF, a CHF and a Policy Control Function, PCF 330, of a telecommunications network. The SMF and CHF may, for example, be SMF 100 and CHF 110 described above with reference to Fig. 1. In general terms, this message flow sequence relates to the situation in which a 25 charging request transmitted from the SMF to the CHF, but a response is not received prior to a loss of connectivity between the SMF and CHF. In particular, message flow sequence 3 may occur when a non-blocking mode of operation is being used for the charging session. 30 As will of course be appreciated, various operations illustrated in Fig. 3 may correspond to operations already described with reference to the previous Figs. For instance, operation 301 may correspond to operation 201 of Fig. 2; operation 302 may correspond to operation 203 of Fig. 2; operation 305 may correspond to operation 204 of Fig. 2; operation 306 may correspond to operation 205 of Fig. 2; operation 307 may 35 correspond to operation 206 of Fig. 2; and operation 308 may correspond to operation 207 of Fig. 2. For conciseness, detailed discussion of various operations already described with reference to the previous Figs, has been omitted. In operation 301, the SMF transmits a charging request (e.g. a 5 “NCHF^ConvergentChargm^ request) to the CHF. For instance, the charging request may be transmitted by a Charging Trigger Function (CTF) included in the CHF. As described above, in the non-blocking mode of operation, SMF may start service delivery to the at least one user responsive to transmitting the charging request, without waiting for a response from the CHF (e.g. at operation 202). 10 In operation 302, a connection loss between the SMF and the CHF occurs. However, unlike in the situation described above with reference to Fig. 2, the loss of connectivity occurs prior to receipt of a response to the charging request. Put another way, because the connection between the SMF and CHF is lost, the CHF is unable to successfully 15 reply to the charging request transmitted by the SMF. As described above with reference to the previous Figs., a connection loss may be deemed to have occurred when the CHF fails to respond to the SMF within a predetermined time interval. In operation 303, a charging characteristics information request (sometimes referred to 20 as a ‘charging plan information request’) is transmitted from the CMF to the PCF 330. For instance, the charging characteristics information request may comprise an “SM (Session Management) Policy Association Modification” request, including an indication that the SMF requires information about the charging characteristics or charging plan type associated with at least one user. In some examples, the charging 25 characteristics information request (e.g. the SM policy association modification request) may include an IE “Plan_type” which is indicative of such a request. In operation 304, information indicative of the charging characteristics for the at least one user is received at the SMF from PCF 330, responsive to the charging 30 characteristics information request transmitted in operation 3O3.Put another way, responsive to receiving the charging characteristics information request from the SMF, PCF 330 may retrieve information indicative of the charging characteristics (e.g. from the UDR as a ‘UDR dump’) and transmit it to the SMF. For instance, the information maybe transmitted from the PCF to the SMF as part of a “SM Policy Association 35 Modification” response. In some examples, the PCF may skip interaction / attempted interaction with other network entities (e.g. the CHF), fetch the required information and transmit this information to the SMF. Based on the information received from the PCF at operation 304, the SMF may 5 determine a type of the charging plan for the at least one user. For instance, the SMF may determine whether or not the charging plan comprises a limited or unlimited network usage quota for a data session for the at least one user. In operation 305, the SMF processes charging data associated with the at least one user 10 using a reduced charging data logging mode selected based on the information received from the PCF in operation 304. In operation 306, a connection between the SMF and the CHF is re-established. 15 In operation 307, responsive to determining that the connection between the SMF and CHF has been re-established, the SMF transmits the collected and logged charging data to the CHF (e.g. as part of a charging release request). In operation 308, the CHF generates a call detail record (CDR) using the collected and 20 logged charging data received from the SMF. For instance, in the case of an unlimited data plan, an ‘unlimited plan-specific’ CDR maybe generated based on the collected and logged charging data without performing any further processing of charging at the CHF. 25 Fig. 4 is a message flow sequence, indicated generally by the reference numeral 4, in accordance with some aspects of the described technology. The message flow sequence 4 shows an example implementation within which aspects of a process, such as that described with reference to Fig. 1, may be performed. 30 In general terms, message flow sequence 4 relates to the situation in which a change in charging plan information is identified during a charging session and, optionally, after a loss of connectivity between the SMF and CHF. For instance, as described below with reference to operation 405, a Tariff Time Change (TTC) maybe identified on the SMF-side. In some examples, the TTC may be indicative of a change from a charging plan 35 which requires less detailed charging data logging (e.g. an unlimited data plan) to a charging plan which requires more detailed charging data logging (e.g. a limited data plan). In other examples, the TTC maybe indicative of a change from to a charging plan which requires more extensive charging data logging to a plan which requires less extensive charging data logging. In yet further examples, the TTC may be indicative of a change between charging plans which require the same level of charging data logging 5 (e.g. where the same charging data logging mode is used to process the charging data for the session). As will of course be appreciated, various operations illustrated in Fig. 4 may correspond to operations already described with reference to the previous Figs. For instance, 10 operations 401 and 406 may correspond to operation 201 of Fig. 2; operations 402 and 407 may correspond to operation 202 of Fig. 2; operation 403 may correspond to operation 203 of Fig. 2; operations 404 and 408 may correspond to operation 204 of Fig. 2; operation 409 may correspond to operation 206 of Fig. 2; and operation 410 may correspond to operation 207 of Fig. 2. For conciseness, detailed discussion of 15 various operations already described with reference to the previous Figs, has been omitted. In operation 401, the SMF transmits a charging request to the CHF. For instance, the charging request maybe transmitted by a Charging Trigger Function (CTF) included in 20 the CHF. In operation 402, the CHF transmits information indicative of charging characteristics for the at least one user to the SMF. Based on the information received from the CHF at operation 202, the SMF may determine a type of the charging plan for the at least one 25 user. As described above with reference to the previous Figs., the information transmitted from the CHF to the SMF may include a flag which identifies the charging plan. In addition or alternatively the flag may identify the reduced charging data logging mode to be used by the SMF for collecting and logging the charging data. Further details of charging characteristics which may be used for identifying a charging 30 plan and / or generating a CDR may be found in 3GPP TS 32.255, Annex A.i. In some examples, such as those in which the charging characteristics correspond to an unlimited charging plan, the information indicative of the charging characteristics may indicate (e.g. via a flag) that the SMF should process charging data in a reduced 35 charging data logging mode. In other words, that the SMF should only log and report to the CHF basic charging information such as session duration or usage counts. In such examples, the flag may comprise an information element (IE) “ReportOnlyUsageCount = TRUE”. In other examples, such as those in which the charging plan is indicated to be a limited 5 charging plan, the information indicative of the charging plan may indicate (e.g. via a flag) that the SMF should process charging data in an increased or full charging data logging mode. In other words, that the SMF should log and report to the CHF more charging information beyond basic information such as session duration or usage counts. For instance, in the increased charging data logging mode, detailed information 10 about individual charging events may be recorded. Such information may include, for instance, a time of call set up, a duration of a call, and / or an amount of data transferred during the chargeable event. In some such examples, the flag may comprise an information element (IE) “ReportOnlyUsageCount = FALSE” 15 In operation 403, a connection loss between the SMF and the CHF occurs. In operation 404, using a charging data logging mode selected based on the information received in operation 402, the SMF processes charging data associated with the at least one user. For instance, in the ‘unlimited data plan’ case, the SMF may 20 update its database with usage data such as call start / end times which can be later used at the CHF-side for generating a CDR and / or updating a policy counter (e.g. to determine a Quality of Service, QoS for the data plan). On the other hand, in the ‘limited data plan’ case, normal collecting and logging of charging data may be performed (i.e. storing full, detailed logs of data usage for transmission to the CHF) 25 occurs. In operation 405, a TTC is identified by the SMF. In some examples, the SMF may identify the TTC via a change in charging characteristics included in subscription data received via the UDM. As described above, such a change may trigger a PDU session 30 modification procedure with the SMF. As a result of the TTC, the SMF needs to trigger a request to close the ongoing CDR and to start a new CDR with the updated charging characteristics. Further details relating to identification of the TTC maybe found in 3GPP TS 32.255, clause 5.2.1.4 (flow based charging) and 5.2.1.6 (QoS based charging). 35 In operation 406, responsive to identifying the TTC in operation 405, the SMF may send a charging update request to the CHF. For instance, the charging update request may comprise a “NCHF_ConvergentCharging_update” request. As will be appreciated, the charging update request may, in some examples, include corresponding information to that included in the charging request (e.g. the “NCHF^ConvergentCharging^create” request) issued at operation 401. 5 In operation 407, the CHF transmits information indicative of further charging characteristics for the at least one user (i.e. a second charging plan for the user) to the SMF responsive to the charging update request transmitted in operation 406. For instance, the information maybe included in a “NCHF_ConvergentChargmg_update” 10 response received at the SMF from the CHF. As will be appreciated, the information transmitted from the CHF to SMF in operation 407 may be similar to that transmitted in operation 402, but a different charging plan for the at least one user may be indicated. Correspondingly, the collecting and logging performed in operation 408 may be adapted based on the received information. 15 It will be appreciated that, if the connection between the SMF and CHF is not reestablished, the process described with reference to operations 406 and 407 may not be possible. In such situations, the SMF may instead obtain information indicative of the charging plan for the at least one user from the PCF, as described with reference to Fig. 20 3. In operation 408, the SMF collects and logs charging data based on the information received in operation 407. In particular, the SMF processes charging data for the at least one user using a charging data logging mode selected based on the information 25 indicative of the further charging characteristics that was received in operation 407. For instance, if the further charging characteristics are indicative of a limited data plan (e.g. a plan with a limited data usage quota for a given period of time), normal collecting and logging of charging data occurs, using a full / increased charging data logging mode. As will be appreciated, if the connection between the SMF and CHF has been re-30 established, this ‘normal’ collecting and logging of charging may involve the sending / receiving of one or more charging data update requests such as described with reference to operations 406 and 407 above. On the other hand, the information received at the SMF in operation 407 may indicate 35 that a reduced charging data logging mode should be used to process charging data at the SMF (e.g. if the indicated data plan is an ‘unlimited’ plan). In some such examples, further processing / bandwidth maybe saved at the SMF / CHF by not transmitting further charging data update requests. As described above with reference to the previous Figs., the information processed at 5 the SMF in operation 408 may be stored / buffered for subsequent transmission to the CHF for use in generating at least one CDR associated with the at least one user. In operation 409, the SMF transmits the collected and logged charging data to the CHF (e.g. as part of a charging release request). Put another way, the SMF may terminate the 10 session by transmitting (e.g. via the CTF of the SMF) a “Nchf^ConvergedCharging^Release” request to the CHF. In some examples, the collected and logged charging data may include charging data associated with both the first charging plan (i.e. before the TTC) and the second charging plan (i.e. after the TTC), for instance in situations where connectivity with the CHF was restored later. In 15 other examples, charging data associated with the first charging plan was transmitted to the CHF as part of the update request transmitted in operation 406, so the charging data transmitted in operation 409 relates to only the second charging plan. Whilst not explicitly depicted in Fig. 4, it will be appreciated that the connection 20 between the SMF and the CHF may be re-established at varying times, which may cause a delay in the transmission of processed charging data to the CHF (e.g. whilst the SMF waits for connection to be re-established. Similarly, lack of connection to the CHF may mean that CMF fetches charging plan information from the PCF (e.g. via a UDR dump), rather than directly from the CHF. It will of course be appreciated that, in 25 examples in which connectivity between the SMF and CHF is not lost during the session, information for use in generating the CDR may be transmitted to the CHF at any time. In operation 410, CHF generates a call detail record (CDR) using the collected and 30 logged charging data received from the SMF in operation 409. As described above with reference to the previous Figs., different types / contents of a CDR may be generated based on the collected and logged charging data received in operation 409. For instance, if charging data relating to an unlimited data plan is received, a less detailed CDR may be generated. In addition or alternatively, if charging data relating to a 35 limited plan is received, a more detailed CDR may be generated. Of course, it will be appreciated that multiple CD Rs may be generated at once corresponding to different data charging plans. Similarly, it will be appreciated that different policy counters may require updating to monitor the usage of different types of data charging plan. In such examples, information suitable for this purpose (e.g. call durations, start / end times) maybe included in the information received from the SMF. In some examples, the 5 generated CDR(s) may be transmitted to the UDR. As will of course be appreciated, various operations illustrated in Fig. 4 may correspond to operations already described with reference to the previous Figs. For instance, operation 401 may correspond to operation 201 in Fig. 2 or operation 301 in Fig. 3; 10 operation 402 may correspond to operation 202 in Fig.2; operation 404 may correspond to operation 203 in Fig. 2; and operation 404 may correspond to operation 204 in Fig. 2. Fig. 5 is a flowchart depicting various operations which maybe performed in 15 accordance with various examples. The operations depicted in Fig. 5 may be performed by a session management function of a telecommunications network. In operation S5.1, the SMF receives information indicative of charging characteristics for at least one user. In some examples, the information indicative of the charging 20 characteristics for the at least one user is received at the SMF from the CHF responsive to a charging request transmitted from the SMF to the CHF. In other examples, the information is received at the at the SMF from a policy control function, PCF, of the telecommunications network responsive to a charging characteristics information request transmitted from the SMF to the PCF. For instance, the charging characteristics 25 information request may be transmitted from the SMF to the PCF responsive to identification of a connection loss between the SMF and the CHF. In some examples, the charging characteristics include an unlimited network usage quota for a data session for the at least one user. 30 In operation S5.2, the SMF processes, using a reduced charging data logging mode selected based on the received information indicative of the charging characteristics, charging data associated with the at least one user. In some examples, operation S5.3 may be performed, in which the SMF transmits the 35 collected and logged charging data to a charging function, CHF, of the telecommunications network for use in generating at least one call detail record / charging detail record associated with the at least one user. In some examples, the collected and logged charging data associated with the at least one user comprises at least one of: a data session duration and an amount of data used by the at least one user. 5 In some examples, operation S5.4 may be performed, in which the SMF receives information indicative of further charging characteristics for the at least one user. In some examples, the further charging characteristics for the at least one user include a limited network usage quota for a data session. 10 In some examples, the charging characteristics and / or the further charging characteristics for the at least one user include at least one of: a time limit for a data session, a data volume limit for a data session (e.g., a total amount of data for a data session), and a change condition for a data session. 15 In some examples, operation S5.5 may be performed, in which the SMF processes, using an increased charging data logging mode selected based on the received information indicative of the further charging characteristics for the at least one user, further charging data associated with the at least one user. 20 As will of course be appreciated, various operations illustrated in Fig. 5 may correspond to operations already described with reference to the previous Figs. For instance, operation S5.1 may correspond to operation 202 in Fig. 2, operation 304 in Fig. 3 or operation 402 in Fig. 4; operation S5.2 may correspond to operation 204 in Fig. 2, 25 operation 305 in Fig. 3 or operation 404 in Fig. 4; operation S5.3 may correspond to operation 206 in Fig. 2, operation 307 in Fig. 3 or operation 404 in Fig. 4; operation S5.4 may correspond to operation 407 in Fig. 4; and operation S5.5 may correspond to operation 408 in Fig. 4. 30 Fig. 6 is a flowchart depicting various operations which may be performed in accordance with various examples. The operations depicted in Fig. 6 may be performed by a CHF. In some examples, operation S6.1 may be performed, in which the CHF receives a 35 charging request transmitted by a SMF. In operation S6.2, which may be responsive to operation S6.1, the CHF transmits to the SMF, information indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging charging data associated 5 with the at least one user. In some examples, operation S6.3 maybe performed, in which the CHF receives charging data associated with the at least one user, the charging data having been processed at the SMF using the reduced charging data logging mode selected based on 10 the information indicative of the charging characteristics. In some examples, operation S6.4 maybe performed, in which the CHF generates, based on the received processed charging data, at least one call detail record, CDR, associated with the at least one user. 15 As will of course be appreciated, various operations illustrated in Fig. 6 may correspond to operations already described with reference to the previous Figs. For instance, operation S6.1 may correspond to operation 201 in Fig. 2, operation 301 in Fig. 3 or operation 401 in Fig. 4; operation S6.2 may correspond to operation 202 in Fig. 2 or 20 operation 402 in Fig. 4; operation S6.3 may correspond to operation 206 in Fig. 2, operation 307 in Fig. 3 or operation 409 in Fig. 4; operation S6.3 may correspond to operation 206 in Fig. 2, operation 307 in Fig. 3 or operation 409 in Fig. 4; operation S6.4 may correspond to operation 207 in Fig. 2, operation 308 in Fig. 3 or operation 410 in Fig. 4. 25 Fig. 7 is a flowchart depicting various operations which maybe performed in accordance with various examples. The operations depicted in Fig. 7 maybe performed by a policy control function, PCF, of a telecommunications network. 30 In some examples, operation S7.1 may be performed, in which the PCF receives a charging characteristics information request transmitted from the SMF. In operation S7.2, which may be responsive to operation S7.1, the PCF transmits to the SMF, information indicative of charging characteristics for at least one user, the 35 information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging data associated with the at least one user. As will of course be appreciated, various operations illustrated in Fig. 7 may correspond 5 to operations already described with reference to the previous Figs. For instance, operation S7.1 may correspond to operation 303 in Fig. 3 and operation S7.2 may correspond to operation 304 in Fig. 3. Fig. 8 is a schematic illustration of an example configuration of a computing apparatus 10 8 which may be configured to perform various operations performed by the SMF, the CHF, and / or the PCF described with reference to Figs.2 to 7. Computing apparatus 8 may comprise control apparatus 800 which is configured to control operation of other components which form part of the computing apparatus 8 15 thereby to enable performance of various operations performed by the SMF, the CHF, and / or the PCF described with reference to Figs. 2 to 7. The computing apparatus 800 may comprise processing apparatus 801 and memory 802. Computer-readable code 802-2A may be computer-readable code for any the SMF, the CHF, or the PCF and the computer-readable code 802-2A maybe stored on the memory 802, which when 20 executed by the processing apparatus 801, causes the control apparatus 800 to perform any of the operations of the SMF, the CHF, or the PCF described herein. In addition, computing apparatus 8 may further include a network interface 806 for communicating with other computing apparatuses 8. 25 Some further details of components and features of the above-described entity / apparatus / device 8 and alternatives forthem will now be described. The control apparatuses described above 800 may comprise processing apparatus 801 30 communicatively coupled with memory 802. The memory 802 has computer readable instructions 802-2A stored thereon, which when executed by the processing apparatus 801 causes the control apparatus 800 to cause performance of various ones of the operations described with reference to Figs. 1 to 7. The control apparatus 800 may in some instances be referred to, in general terms, as “apparatus”. The processing apparatus 801 maybe of any suitable composition and may include one or more processors 801A of any suitable type or suitable combination of types. Indeed, the term “processing apparatus” should be understood to encompass computers having differing architectures such as single / multi-processor architectures and 5 sequencers / parallel architectures. For example, the processing apparatus 801 may be a programmable processor that interprets computer program instructions 802-2A and processes data. The processing apparatus 801 may include plural programmable processors. Alternatively, the processing apparatus 801 maybe, for example, programmable hardware with embedded firmware. The processing apparatus 801 may 10 alternatively or additionally include one or more specialised circuit such as field programmable gate arrays FPGA, Application Specific Integrated Circuits (ASICs), signal processing devices etc. In some instances, processing apparatus 801 may be referred to as computing apparatus or processing means. 15 The processing apparatus 801 is coupled to the memory 802 and is operable to read / write data to / from the memory 802. The memory 802 may comprise a single memory unit or a plurality of memory units, upon which the computer readable instructions (or code) 802-2A is stored. For example, the memory 802 may comprise both volatile memory 802-1 and non-volatile memory 802-2. In such examples, the 20 computer readable instructions / program code 802-2A may be stored in the non volatile memory 802-2 and may be executed by the processing apparatus 801 using the volatile memory 802-1 for temporary storage of data or data and instructions. Examples of volatile memory include random-access memory (RAM), dynamic random-access memory (DRAM), and synchronous dynamic random-access memory 25 (SDRAM) etc. Examples of non-volatile memory include read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable readonly memory (EEPROM), flash memory, optical storage, magnetic storage, etc. The memory 802 may be referred to as one or more non-transitory computer readable 30 memory medium or one or more storage devices. Further, the term ‘memory’, in addition to covering memory comprising both one or more non-volatile memory and one or more volatile memory, may also cover one or more volatile memories only, one or more non-volatile memories only. In the context of this document, a “memory” or “computer-readable medium” may be any media or means that can contain, store, 35 communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. The computer readable instructions / program code 802-2A may be pre-programmed into the control apparatus 800. Alternatively, the computer readable instructions 7802-2A may arrive at the control apparatus via an electromagnetic carrier signal or may be 5 copied from a physical entity 9 such as a computer program product, a memory device or a record medium such as a compact disc read-only memory (CD-ROM) or digital versatile disc (DVD) an example of which is illustrated in Fig. 9. The computer readable instructions 802-2A may provide the logic and routines that enables the entity / device / apparatus 8 to perform the functionality described above. The 10 combination of computer-readable instructions stored on memory (of any of the types described above) may be referred to as a computer program product. In general, references to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device as instructions for a processor or configured or 15 configuration settings for a fixed function device, gate array, programmable logic device, etc. If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the 20 above-described functions may be optional or may be combined. Similarly, it will also be appreciated that the flow diagrams of Figs. 2 to 7 are examples only and that various operations depicted therein may be omitted, reordered and / or combined. Although the methods and apparatuses have been described in connection with an E-25 UTRA or 5G network, it will be appreciated that they are not limited to such networks and are applicable to radio networks of various different types. Although various aspects of the methods and apparatuses described herein are set out in the independent claims, other aspects may comprise other combinations of features 30 from the described embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. It is also noted herein that while various examples are described above, these descriptions should not be viewed in a limiting sense. Rather, there are several 35 variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A method comprising:receiving, at a session management function, SMF, of a telecommunications network, information indicative of charging characteristics for a user; and5 determining, at the SMF whether to use a reduced charging data logging mode,based on the information indicative of the charging characteristics, to collect to log charging data associated with the user; andcollecting and logging charging data associated with the user.io 2. The method of claim 1, further comprising:transmitting, by the SMF, the charging data associated with the user to a charging function, CHF, of the telecommunications network for use in generating at least one call detail record, CDR, associated with the user.15 3. The method of claim 1 or claim 2,wherein the information indicative of the charging characteristics for the user is received at the SMF from a charging function, CHF, of the telecommunications network responsive to a charging data request for charging data transmitted by the SMF to the CHF.

204. The method of claim 1 or claim 2,wherein the information indicative of the charging characteristics for the user is received at the SMF from a policy control function, PCF, of the telecommunications network is received in response to a charging characteristics information request for 25 the information indicative of the charging characteristics which is transmitted by the SMF to the PCF.

5. The method of claim 4,wherein the charging characteristics information request is transmitted from30 the SMF to the PCF responsive to identification of a connection loss between the SMF and a charging function, CHF, of the telecommunications network.

6. The method of any preceding claim,wherein the charging data associated with the user comprises at least one of: a 35 data session duration and an amount of data used by the one user.7- The method of any preceding claim, wherein the charging characteristics include an unlimited network usage quota for the data session.5 8. The method of any preceding claim, further comprising:receiving, at the SMF, information indicative of further charging characteristics for the user; anddetermining, at the SMF to use an increased charging data logging mode based on the information indicative of the further charging characteristics for the one user to io collect and log further charging data associated with the user; andcollecting and logging further charging data.

9. The method of claim 8, wherein the further charging characteristics for the user include a limited data 15 usage quota for the data session.

10. The method of any preceding claim, wherein the charging characteristics for the user include at least one of: a time limit for the data session for the user, a limit for an amount of the data session, and a20 change condition for the data session.

11. The method of any preceding claim, wherein collecting11. A method comprising:25 transmitting, by a charging function, CHF, of a telecommunications network toa session management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging data associated with the at user.3012. The method of claim 11, wherein the providing information indicative of the charging characteristics for the one user in a response to receipt, at the CHF, a charging data request for charging data transmitted from the SMF.

13. The method of claim 11, further comprising:receiving, at the CHF, charging data associated with the at least one user, the charging data having been collected and logged at the SMF based on the reduced charging data logging mode selected based on the information indicative of the charging characteristics; and5 generating, at the CHF based on the charging data, at least one call detailrecord, CDR, associated with the one user.

14. A method comprising:transmitting, from a policy control function, PCF, of a telecommunications10 network to a session management function, SMF, of the telecommunications network, information indicative of charging characteristics for at least one user, the information indicative of the charging characteristics being for use in selecting a reduced charging data logging mode for collecting and logging charging data associated with the user.15 15. The method of claim 14,wherein the information indicative of the charging characteristics for the at least one user is transmitted to the SMF responsive to a receiving, at the PCF, a charging characteristics information request transmitted from the SMF.20 16. The method of claim 15,wherein the charging characteristics information request comprises a session management, SM, policy association modification request.34

Images