Session control and services
TS 23.228 describes the IMS architecture. Session control functions such as CSCF take part in registration and signaling routing. Application servers can execute service logic according to the design adopted for the proposed deployment.
The project should distinguish signaling from media. Establishing a session does not prove that audio reaches participants correctly. Terminals, codecs, connectivity and integration points need to be assessed along the path actually used by the call.
Connectivity and applications have different roles
Having LTE or 5G access does not by itself demonstrate that an application uses IMS. Likewise, calling a product PoC does not establish an IMS architecture or compliance with the mission critical services defined by 3GPP.
We recommend requesting a diagram showing components, interfaces and versions. Identify who manages users and services, which terminals are supported and how the solution connects with the existing environment. The scope should translate the architecture into verifiable functions.
Test interfaces and actual use
ETSI develops and validates test specifications for core networks, covering aspects such as interoperability and conformance. For a deployment, these references need to be linked to the components and interfaces actually included within the approved scope.
An acceptance plan can check registration, call establishment, media in both directions and behavior after interruptions. Document approved capabilities and limitations. A terminal or server update may justify testing the affected functions again before accepting the revised configuration.
What to assess for your project
- Separate transport, session control and applications.
- Identify implemented interfaces and versions.
- Check supported terminals and capabilities.
- Test calls, media and recovery.
COM3
How COM3 can help
COM3 can help assess voice and multimedia requirements, organize the proposed architecture and structure integration tests. When the solution involves IMS, the project can include interface documentation and validation of contracted functions, working with the suppliers responsible for each component within the agreed deployment scope.
Topics in this article
Further reading and references
Technical sources consulted for the fundamentals of this content. Project recommendations are an editorial synthesis by COM3.