Method and device for establishing an emergency call from a vehicle

Abstract

The invention relates to a method for transmitting data relating to a vehicle during an emergency call triggered from said vehicle, comprising steps of obtaining (301) data representative of a context for triggering the emergency call; selecting (303) a particular transmission mode for said data relating to the vehicle according to the context data obtained by consulting a database comprising one or more records in which a call trigger context data item is associated with a particular transmission mode and a status representative of the success or failure of a prior attempt to transmit data relating to the vehicle according to said transmission mode; and establishing a communication to an emergency call processing center comprising the transmission (304) of said data relating to the vehicle according to the selected transmission mode.The invention also relates to a device suitable for implementing such a method. Figure 3.

Description

Title of the invention: Method and device for establishing an emergency call from a vehicle Technical field

[0001] The invention belongs to the field of telecommunications and relates more particularly to a method for improving the time taken to establish an emergency call sent from a vehicle via an Internet-type network. PRIOR ART

[0002] The eCall service is a system standardized by ETSI and made mandatory by European legislation for emergency calls made by vehicles, allowing the establishment of real-time communications and the transmission of contextual data from a vehicle alert unit (IVS, for "In-Vehicle System in English) to an emergency call processing center (PSAP for "Public Safety Answering Point" in English).

[0003] An eCall call includes in particular the transmission of a context data block (MSD for Minimum Set of Data) comprising information concerning the vehicle, for example its geolocation. When the communication is established on a circuit-switched network, the MSD block is transmitted by modulation of the audio signal in the band by a modem.

[0004] The deployment of packet-switched mobile networks intended to replace GSM-type circuit-switched mobile networks in the medium term has given rise to the development by ETSI of new standards for the support of the eCall service by these networks. The NG-eCall (New Generation eCall) standard is thus specified in the ETSI TR 103 140 document and defines in particular the mechanisms for establishing VoIP (Voice Over IP) emergency calls based on the SIP (Session Initiation Protocol) protocol.

[0005] The coexistence of these different standards poses particular problems. Indeed, it is not guaranteed that the vehicle, the communication network and the emergency call processing center support the same version of the standard. In order to ensure interoperability and continuity of the emergency service, fallback mechanisms are provided in the ETSI TR 103 140 specification. For example, in the event of failure to establish a VoIP emergency call, the standard provides that a new attempt is initiated using GSM-type circuit communication.

[0006] Such a fallback mechanism, however, has the disadvantage of lengthening the time taken to establish communication, which can delay the response time of emergency services in the event of an accident.

[0007] For this purpose, it has been proposed to transmit an indicator making it possible to signal to the vehicle that the NG-eCall service is supported both by the network to which the vehicle is connected and by at least one emergency call processing center accessible via this network. Thus, upon receipt of such an indicator, a vehicle can decide to send a new generation emergency call (NG-eCall) or to fall back on a communication compliant with the eCall standard on GSM.

[0008] However, these mechanisms do not guarantee complete interoperability. Indeed, the MSD data block can be transmitted in different ways. The MSD block can be transmitted in the signaling, for example in a SIP INVITE message or in a SIP INFO message, but it can also be modulated in the audio signal. Thus, a PSAP can declare itself capable of receiving NG-eCall communications while being configured to receive the MSD in the audio band, while other PSAPs can be configured to receive the MSD in the signaling. Other scenarios related to the MSD transmission mode can lead to a call failure, for example an IMS network can reject a call if it does not expect to receive an MSD in the signaling or simply delete the MSD from the message if it does not know how to interpret it.In other cases, processing applied by the network to the audio signal may alter the transmission of the MSD when it is transmitted in the band, etc. In these conditions, several call attempts may be necessary for the MSD to be correctly transmitted, which further delays the PSAP taking into account the alert.

[0009] There is therefore a need for a method of establishing an emergency call which does not have the aforementioned drawbacks. Summary of the invention

[0010] To this end, a method is proposed for transmitting data relating to a vehicle when an emergency call is triggered from said vehicle: - Obtaining (101) data representative of a context for triggering the emergency call, - Selection (102) of a particular transmission mode of said data relating to the vehicle according to the context data obtained, - Establishment (103) of a communication to an emergency call processing center, the communication comprising the transmission (104) of said data relating to the vehicle according to the selected transmission mode.

[0011] The method is remarkable in that the step of selecting a transmission mode according to a call triggering context comprises consulting a database comprising one or more records in which a call triggering context data item is associated with a transmission mode by particular and a status representative of the success or failure of an attempt to previously transmit data relating to the vehicle according to said transmission mode.

[0012] Thus, the mode of transmission of vehicle-related data during an emergency call (for example the mode of transmission of MSD data during an eCall call) is determined according to the context in which the call is made. For this purpose, it is proposed to use a call history in which the results of transmission attempts during previous calls have been stored, depending on the context and the transmission mode. It is thus possible to determine a transmission mode that is adapted to the context from past experience.

[0013] The probability that the vehicle data block is transmitted correctly is thus improved and a delay in handling the call is avoided in the event of incompatibility of the transmission mode with the network and / or the system used by the emergency call processing center.

[0014] According to a particular embodiment, the method is such that it further comprises, when the emergency call is terminated, a step of storing in said database a record comprising at least the call trigger context data obtained, the transmission mode selected for the transmission of said data relating to the vehicle, and a status representative of the success or failure of said transmission according to said transmission mode.

[0015] The database from which a transmission mode for the vehicle data is selected is thus updated with each call.

[0016] According to a particular embodiment, the method is such that it further comprises a step of transmitting the stored recording to a server.

[0017] In this way, a server can create a database from the information sent back by a plurality of vehicles. Such a database makes it possible to precisely define geographical areas in which a particular transmission mode is available or a list of telecommunications operators or communication networks supporting a particular transmission mode of data relating to the vehicle during an emergency call.

[0018] According to a particular embodiment, the method is such that the database comprises at least one record downloaded from a server.

[0019] Thus, a database created by a server from data collected by a server in which transmission modes are associated with contextual data is made available to vehicles. In this way, a vehicle can benefit from the experience acquired by other vehicles in a similar context to select a transmission mode with the greatest chance of success. For example, a vehicle can receive from a server a table including associations between geographical areas and / or network (or network operator) identifiers and supported transmission modes. From such a table, a vehicle can initially select a data transmission mode that has the best chance of success.

[0020] According to a particular embodiment, the method is such that the data representative of the context for triggering a communication comprises at least one geographical location and / or an identifier of a communication network.

[0021] It is thus proposed to associate the success or failure of a data transmission according to a particular transmission mode with a geolocation of the vehicle at the time of the call and / or the communication network used. It is thus possible to define geographical areas or telecommunications network operators in which a mode of transmission of data relating to the vehicle can be used successfully in the event of an emergency call.

[0022] In a particular embodiment, the first and second modes of transmission of data relating to the vehicle are selected from the following transmission modes: - transmission of a block of data relating to the vehicle in a signaling message and - transmission includes the transmission of a block of vehicle-related data by data modulation into an audio signal.

[0023] It is thus envisaged that the data relating to the vehicle are transmitted in a signaling message (“outband” transmission in English) or by modulation of the audio signal by a modem (“inband” transmission in English).

[0024] According to a particular embodiment, the signaling message is a SIP INVITE message or a SIP INFO message.

[0025] In the case of an outband transmission, that is to say in a signaling message, the block of data relating to the vehicle (for example an MSD block) can be transmitted in a SIP INVITE message sent when an emergency call is triggered or in a SIP INFO message, for example in response to a transmission request sent by an emergency call processing center.

[0026] According to another aspect, the invention relates to a device for transmitting data relating to a vehicle during an emergency call triggered from said vehicle comprising a processor coupled to a memory in which program instructions are recorded configured to implement the following steps, when they are executed by the processor: - Obtaining data representative of a context for triggering the emergency call, - Selection of a particular mode of transmission of said data relating to the vehicle according to the context data obtained, the selection comprising consulting a database comprising one or more records in which a call trigger context data is associated with a particular transmission mode and a status representative of the success or failure of a prior attempt to transmit data relating to the vehicle according to said transmission mode, and - Establishing a communication to an emergency call processing center, the communication including the transmission of said data relating to the vehicle according to the selected transmission mode.

[0027] According to yet another aspect, the invention relates to a vehicle communication unit comprising such a device.

[0028] Also provided is a computer program comprising instructions for executing the steps of a call setup method as described above, when the instructions are executed by a processor.

[0029] Finally, the invention relates to an information medium readable by a processor on which is recorded a computer program comprising instructions for executing the steps of a call establishment method as described above.

[0030] The information medium may be a non-transitory information medium such as a hard disk, a flash memory, or an optical disk for example.

[0031] The information medium may be any entity or device capable of storing instructions. For example, the medium may comprise a storage means, such as a ROM, RAM, PROM, EPROM, a CD ROM or even a magnetic recording means, for example a hard disk.

[0032] On the other hand, the information carrier may be a transmissible carrier such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means.

[0033] Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

[0034] The various embodiments or features mentioned above may be added independently or in combination with each other, to the steps of the prediction method.

[0035] The devices, communication unit, information media and programs have at least advantages similar to those conferred by the method to which they relate. Brief description of the drawings

[0036] Other characteristics, details and advantages of the invention will appear on reading of the detailed description below, and to the analysis of the appended drawings, among which:

[0037] [Fig. 1] [Fig. 1] shows an environment adapted to implement a method of transmitting data relating to a vehicle during an emergency call, according to a particular embodiment,

[0038] [Fig.2] [Fig.2] is a timing diagram showing messages exchanged between a vehicle, a communications network and a call processing center when establishing an NG-eCall emergency call,

[0039] [Fig.3] [Fig.3] is a flowchart illustrating the main steps of a process transmission of data relating to a vehicle during an emergency call, according to a particular embodiment,

[0040] [Fig.4] [Fig.4] illustrates the architecture of a device suitable for implementing a method of transmitting data relating to a vehicle during an emergency call, according to a particular embodiment. DETAILED DESCRIPTION

[0041] [Fig. 1] illustrates an environment suitable for implementing a method for transmitting data relating to a vehicle during an emergency call, according to a particular embodiment.

[0042] [Fig.l] shows a vehicle 100 comprising a communication device (IVS) adapted to establish emergency calls to an emergency call processing center 102 (PSAP) via a cellular communication network 101. The call can be triggered by an action of an occupant of the vehicle on a button provided for this purpose or automatically, for example in the event of an accident. Such a system is known under the name "eCall" in Europe (for Emergency Call in English).

[0043] The eCall standard provides for the establishment of a two-way audio communication allowing an operator 104 of the processing center 102 to communicate with the occupants of the vehicle 100 in order to obtain information on the reasons for the call. The eCall service also provides for the sending by the vehicle of a set of data relating to the vehicle (MSD, for Minimum Set of Data in English) allowing the operator to obtain additional information. This data includes for example the geographical coordinates of the vehicle, a VIN number (for Vehicle Identification Number in English) making it possible to identify the make and model of the vehicle, the number of occupants, etc. This data makes it possible to improve the handling of the emergency.

[0044] In a first version of the eCall standard, the communication network 101 is a circuit-switched (CS) cellular network, for example a GSM network. In such a case, the vehicle's communication device (IVS) comprises a modem adapted to modulate the vehicle-related data (MSD) in order to transmit them to the processing center 102 in the audio signal. The transmission of the data is then called "inband". The emergency call processing center comprises equipment 103 configured to demodulate the data transmitted by the vehicle 100 in the audio signal and make them available to the operator 104.

[0045] The NG-eCall (New Generation eCall) standard is designed to establish communication between the vehicle 100 and the processing center 102 via a packet-switched (PS) cellular access network of the 4G or 5G type and an IMS core network. This is referred to as "eCall over IMS." In this case, it is not necessary to modulate the MSD data to transmit them in the band, the data block being able to be transmitted in the signaling. It is noted that a vehicle compatible with the NG-eCall standard must also be compatible with the first-generation eCall standard in order to allow emergency calls to be triggered even when the network and / or the call processing center is not compatible with the NG-eCall standard.

[0046] [Fig. 2] is a timing diagram showing messages that may be exchanged between a vehicle such as vehicle 100 and a call processing center when establishing a SIP-compliant NG-eCall emergency call.

[0047] Conventionally, when an emergency call is triggered, the vehicle sends to the network 101 a message 200 of the SIP INVITE type comprising an MSD data block. The network 101 routes the message to the call processing center 102. The processing center 102 acknowledges the correct reception of the MSD data block in a response message 202 of the SIP 200 OK type. The network 101 forwards the 200 OK response and the acknowledgment of the MSD data to the vehicle 100. A two-way RTP (Real Time Protocol) audio communication channel is then established between the vehicle 100 and the emergency call processing center 102. In the event of an error in receiving the MSD block by the call processing center 102, the SIP 200 OK response may include a negative acknowledgment to signal to the vehicle 100 that the MSD data has not been received.

[0048] The NG-eCall standard also provides that the emergency call processing center 102 can request a new transmission of an MSD data block by means of a SIP INFO message 204. Upon receipt of such a message, the vehicle can transmit an updated version of the MSD block in a response message 205.

[0049] The deployment of IP (Internet Protocol) communication services such as 1TMS (Internet Multimedia Subsystem) is not homogeneous. Thus, in certain circumstances, depending on the operator and / or the geographical area for example, IP communications may not be available end-to-end. For example, the vehicle 100 and the communication network 101 may be compliant with the NG-eCall standard and while the call processing center 102 may be of old generation and support only the old generation eCall service in which the MSD data block is transmitted by modulation in the audio band. The IMS core network generally comprises a gateway to ensure the continuity of the audio call to the call center 102. However, such a gateway does not always ensure the in-band transmission of an MSD data block received in the signaling. In such a case, the vehicle 100 may decide to retransmit the MSD block by modulating it in the band when it does not receive an acknowledgment to confirm the correct reception of the data by the processing center 102.While compatibility can be ensured in this way, such an arrangement lengthens processing time and degrades the quality of emergency response. In addition, processing carried out by the core network on the audio signal, for example possible transcoding, can degrade the audio signal and make it difficult or even impossible to decode the modulated data in it.

[0050] [Fig. 3] is a flowchart illustrating the main steps of a method of transmission by the vehicle 100 described with reference to [Fig. 1], of data relating to a vehicle during a call to the emergency call processing center 102, according to a particular embodiment.

[0051] During a first step 300, the vehicle 100 obtains a database comprising at least one association between a context data item and a particular transmission mode to be preferably used to transmit a block of MSD data to the emergency call processing center 102. For example, the database may contain records making it possible to associate preferred transmission modes with particular geographical areas and / or network operator identifiers and / or identifiers of access points to a communication network.

[0052] The database may be stored in a memory of the vehicle and contain records that are downloaded by the vehicle from a server via an Internet connection.

[0053] The method comprises a step 301 during which context data is obtained. The context data relates to a current time and comprises, for example, a geographical location of the vehicle or an identifier of a network operator to which the vehicle is connected via a wireless communication interface. Step 301 can thus be repeated regularly so that the vehicle 301 has at each time context data representative of its current situation. In other exemplary embodiments, obtaining such data context can be performed punctually, for example when the emergency call is triggered.

[0054] The geographical location is for example obtained by means of a GNSS receiver connected to the vehicle's communication system, for example via a CAN (Controller Area Network) communication bus. Alternatively or additionally, the geographical location can be determined by a cellular communication module, for example from an identifier of a base station to which the vehicle's communication interface is connected. The geographical context data can also be determined from an MCC (for Mobile Country Code in English).

[0055] In a particular embodiment, the context data obtained may comprise an operator identifier of a communications network such as an MNC (for Mobile Network Code in English).

[0056] In step 302, an emergency call is triggered from the vehicle 100 to the emergency call center 102. The call may be triggered by an action of an occupant of the vehicle or automatically, for example following the detection of an emergency situation such as sudden deceleration detected by a sensor of the vehicle or the triggering of an airbag. A communication to a predefined emergency number, for example to the number 112, is then initiated by a communication unit of the vehicle.

[0057] During a step 303, a particular transmission mode of an MSD data block is selected as a function of the context data obtained. For this, the vehicle matches the context data obtained with records in the database obtained in step 300 to determine a transmission mode associated with the context data. For example, the vehicle selects a particular transmission mode by selecting from the database the transmission mode which is associated with the geographical area in which it is located, and / or as a function of an identifier of the operator of the communication network to which it is connected and / or according to an identifier of the network to which it is connected.For example, one transmission mode may include adding the MSD data into the body of a SIP INVITE type signaling message used to initiate communication, or in another example, the MSD data may be modulated into the audio signal transmitted to the call processing center 102 using a modem.

[0058] When the database does not include a record associated with the current context determined by the vehicle, a default transmission mode can be selected.

[0059] In step 304, an attempt is made to transmit an MSD data block to the emergency call processing center 102 using the transmission mode selected in step 303. For example, the vehicle 100 may attempt to transmit the MSD block in a SIP INVITE signaling message in accordance with the IETF standards RFC8174 “Next-Generation Pan-European eCall” and RFC 7852 “Additional Data Related to an Emergency Call”.

[0060] During a step 305, the vehicle 100 determines a status representative of the success or failure of the attempt to transmit the data block according to the selected transmission mode. The status can be determined by the reception or not of an acknowledgment from the processing center 102, for example a SIP 200 OK type message comprising an indication that the MSD block has been received. Conversely, a transmission failure can be determined by the non-receipt of an acknowledgment after the expiration of a timeout, or of a negative acknowledgment indicating an error in reception of the data block by the processing center 102.

[0061] The method comprises a step 306 of storing in a database a record comprising at least the call trigger context data obtained in step 301, the transmission mode selected in step 303 for the transmission of the MSD, as well as the status obtained in step 305. According to a particular embodiment, a record is added to the database only in the event of successful transmission of the MSD data.

[0062] Optionally, the method may finally comprise a step 307 during which the recording stored in step 306 is transmitted to a server. In this way, the server can collect associations between contexts, transmission modes and statuses from a plurality of vehicles in order to constitute, enrich and update a database. The recordings of this database can thus be transmitted to vehicles so that they can select a transmission mode adapted to the context in which an emergency call is triggered.

[0063] [Fig.4] shows the architecture of a device 400 for transmitting data relating to a vehicle during an emergency call.

[0064] The device 400 comprises a storage space 402, for example a memory MEM, a processing unit 401 equipped for example with a processor PROC. The processing unit can be controlled by a program 403, for example a computer program PGR, implementing the method for transmitting data relating to a vehicle described with reference to [Fig. 3] and in particular the steps of obtaining data representative of a context for triggering the emergency call; of selecting a particular transmission mode of said data relating to the vehicle according to the context data obtained by consulting a database comprising one or more records in which a call trigger context data is associated with a transmission mode by particular and a status representative of the success or failure of an attempt to previously transmit vehicle-related data according to said transmission mode; and establishing a communication to an emergency call processing center including the transmission of said vehicle-related data according to the selected transmission mode.

[0065] At initialization, the instructions of the computer program 403 are for example loaded into a RAM (Random Access Memory) memory before being executed by the processor of the processing unit 401. The processor of the processing unit 401 implements the steps of the method according to the instructions of the computer program 403.

[0066] For this purpose, in addition to the memory 402 and the processor 403, the device comprises a communication unit 404, for example a 2G, 3G, 4G, 5G, WiFi or Wimax cellular communication interface, enabling the establishment of voice communications with an emergency call processing center via a communication network and the transmission of vehicle-related data, for example an MSD data block. The communication unit is particularly suitable for establishing IP communications, for example VoIP (Voice Over IP) communications using a data connection.According to a particular embodiment, the communication unit 404 is adapted to establish communications in accordance with the SIP (Session Initiation Protocol) protocol via an IMS (Internet Multimedia Subsystem) communication network and to transmit an MSD data block in SIP signaling messages, for example in SIP INVITE, SIP INFO messages or in SIP 200 OK responses. For this, the communication unit can be controlled by computer program instructions recorded for example in the memory 402 of the device 400 and adapted to implement a protocol stack conforming to a VoIP communication standard, for example a SIP or H.323 stack.

[0067] The device 400 also comprises a module 405 for determining context data for triggering an emergency call. According to a particular embodiment, the module 405 is implemented by computer program instructions configured to obtain a geographical location of the vehicle at the time of triggering an emergency call. For this, the module 405 is for example adapted to communicate with a GNSS receiver 406 (for Global Navigation Satellite System in English) and obtain geographical coordinates, such as a longitude and a latitude, corresponding to the location of the device. The module 405 for determining context data can further be configured to obtain an identifier of an operator of a communication network to which the device is connected via the communication module 404, for example example an MCC, and / or an identifier of a communication network and / or an access point to a cellular network. For this, the module 405 can be configured by computer program instructions to interrogate the communication module 404 and obtain such context data.

[0068] The device 400 also comprises a database 407. The database 407 is for example an SQL (Structured Query Language) database stored in the memory 403 of the device 400. The database 407 is configured to store associations between context data such as the context data determined by the determination module 405, modes of transmission of data relating to the vehicle and statuses representative of a success or failure of a transmission of a block of data to an emergency call processing center in said context.

[0069] According to a particular embodiment, the database 407 comprises at least one record downloaded from a server. For this, the communication unit 404 can be configured by computer program instructions to make a request to a server of a communication network and receive in response to this request at least one association between a context data item (such as a geographical area, a network operator identifier, a communication network access point) and a zone transmission mode suitable for the transmission of a data block during an emergency call according to said transmission mode.

[0070] The device 400 also comprises a module 408 for transmitting a block of data relating to the vehicle during a communication to an emergency call processing center. The module 408 can be configured by computer program instructions adapted to implement at least two modes of transmitting a block of MSD data to an emergency call processing center.

[0071] According to a particular embodiment, the module 408 is configured to offer an MSD data transmission mode called “inband”. For this, the module 408 comprises a modem adapted to modulate MSD data in an audio signal transmitted to a call center during a communication.

[0072] According to a particular embodiment, the module 408 is configured to offer an MSD data transmission mode called “outband”. For this, the module 408 is controlled by program instructions configured to format the MSD data block in a format suitable for transmission in a SIP signaling message. For example, the instructions are adapted to structure the data in accordance with the IETF RFC7852 standard in order to include them in a SIP signaling message that can be transmitted by the communication module 404.

[0073] The device finally comprises a module 409 for selecting a transmission mode. of an MSD data block. The selection module 409 may be implemented by computer program instructions configured to obtain context data from the determination module 405 when an emergency call is triggered, and to search the database 407 for a transmission mode adapted to the obtained context data. For example, the module 409 may use a comparator to compare the obtained context data with context data included in records of the database 407 in order to identify one or more records comprising a similar context and thus obtain a transmission mode adapted to said context.

[0074] The communication module 404 is further configured to transmit, according to the transmission mode selected by the module 409, data relating to the vehicle, such as an MSD data block, during a communication to a call processing center.

[0075] According to a particular embodiment, the communication module 404 is further configured to determine a status representative of the success or failure of a transmission of data relating to the vehicle according to a particular transmission mode. For example, the module 404 can be controlled by program instructions configured to analyze an error code received in response to the transmission of data, to determine the absence of receipt of an acknowledgment following the transmission of said data, or conversely to determine that the data has been transmitted successfully. The communication module can further be configured by instructions to store in the database 407 the determined status as well as data representative of the context in which the communication was established and the transmission mode used.According to a particular embodiment, the communication module 404 is controlled by instructions configured to transmit the stored recording to a server.

[0076] According to a particular embodiment, the device is integrated into a vehicle communication system, for example a TCP (Telecommunication Control Unit in English) or an emergency call system of the eCall or NG-eCall type.

Claims

1.

2.

3.

4. Claims Method for transmitting data relating to a vehicle during an emergency call triggered from said vehicle comprising the following steps: - Obtaining (101) data representative of a context for triggering the emergency call, - Selection (102) of a particular transmission mode of said data relating to the vehicle according to the context data obtained, - Establishment (103) of a communication to an emergency call processing center, the communication comprising the transmission (104) of said data relating to the vehicle according to the selected transmission mode, The method being characterized in that the data representative of the triggering context comprises at least a geographical location of the vehicle and / or an identifier of a communication network to which a wireless communication interface of the vehicle is connected, and the selection of a transmission mode according to a call triggering context comprises the consultation of a database comprising one or more records in which a call triggering context data item is associated with a particular transmission mode and a status representative of the success or failure of a prior attempt to transmit data relating to the vehicle according to said particular transmission mode.Method according to claim 1 such that it further comprises, when the emergency call is completed, a step of storing in said database a record comprising at least the call trigger context data obtained, the transmission mode selected for the transmission of said data relating to the vehicle, and a status representative of the success or failure of said transmission according to said transmission mode. Method according to claim 2 such that it further comprises a step of transmitting the stored recording to a server. A method according to any preceding claim wherein the database comprises at least one tele- downloaded from a server.

5. Method according to any one of the preceding claims in which a mode of transmission of a block of data relating to the vehicle is selected from the following transmission modes: - Transmission of the data in a signaling message, and - Transmission by modulation of the data in an audio signal.

6. The method of claim 5 wherein the signaling message is a SIP INVITE message or a SIP INFO message.

7. Device for transmitting data relating to a vehicle during an emergency call triggered from said vehicle comprising a processor (401) coupled to a memory (402) in which are recorded program instructions (403) configured to implement the following steps, when executed by the processor: - Obtaining data representative of a context for triggering the emergency call, the data representative of the triggering context comprising at least a geographical location of the vehicle and / or an identifier of a communication network to which a wireless communication interface of the vehicle is connected, - Selecting a particular mode of transmission of said data relating to the vehicle according to the context data obtained,the selection comprising consulting a database comprising one or more records in which a call trigger context data item is associated with a particular transmission mode and a status representative of the success or failure of a prior attempt to transmit data relating to the vehicle according to said particular transmission mode, and - Establishing a communication to an emergency call processing center, the communication comprising the transmission of said data item relating to the vehicle according to the selected transmission mode.,

8. A vehicle communication unit comprising a device according to claim 7.

9. A processor-readable information medium on which is recorded a computer program comprising instructions for executing the steps of a transmission method according to any one of claims 1 to 6.

10. A computer program comprising instructions for carrying out the steps of a transmission method according to any one of claims 1 to 6, when the program is executed by a processor.

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