S-CSCF Server Routing for IMS Telephony Subscribers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current IMS networks lack the capability to route VoIP calls from IP networks to IMS subscribers who only have data services and use CS networks for telephone services, leading to call rejection or compatibility issues, which are commercially undesirable.
Innovation Solution
Implementing a routing function within the S-CSCF server to determine if the requested service is a telephone service and if the user has subscribed to it, and if not, directing the service request to a separate CS network, ensuring service consistency and compliance with telephone number standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IMS network routes VoIP calls to all IMS subscribers uniformly, then the network architecture remains simple, but calls to subscribers without telephone service subscriptions are rejected or incompatible
Solution Approach 1:
The S-CSCF server performs preliminary checks before call routing to determine whether the called subscriber has subscribed to telephone services. By checking the subscriber's service profile in advance and identifying the appropriate network (IMS or CS) before routing the call, the system ensures reliable call delivery without requiring complex real-time routing decisions during call establishment
Solution Approach 2:
The routing function is segmented into distinct operational paths: one path handles subscribers with IMS telephone service subscriptions, while another path handles subscribers without such subscriptions (routing to CS networks). This segmentation allows the system to maintain simple architecture for each path while achieving reliable overall routing through the S-CSCF server's ability to select the appropriate path based on subscriber profile
2Manufacturing precision
If the S-CSCF server implements comprehensive service verification, then service consistency is maintained, but processing time increases
Solution Approach 1:
Service verification is performed as a preliminary action during call routing setup. The S-CSCF server checks the called subscriber's service profile before call establishment to determine the appropriate network type. Since this verification occurs before the call is actually set up, it ensures service consistency without adding noticeable delay to the user experience
Solution Approach 2:
The patent uses lightweight service profile data structures that can be quickly queried and discarded after use. These temporary data objects enable rapid verification of service consistency without requiring complex, time-consuming database queries or prolonged processing
Data Source
Figure 1
AI summary
A serving call server control function (S-CSCF) server in an IMS network is configured to receive a service request targeting a client device belonging to the IMS network and under the charge of the S-CSCF server. The S-CSCF server uses information elements contained in the service request to perform verifications, including: determining that the requested service is a telephone service; and determining that the user of the target client device targeted in the service request has not subscribed to a telephone service with the operator of the IMS network. If the result of the verifications is positive, the S-CSCF server directs the service request to a telephone network to which the target client device belongs. The server is applicable to subscribers of an IMS network benefiting from non-conversational services in packet mode from the IMS network, but having telephone services supplied thereto by a circuit-switched network.