2nd IMS Plugtests

ETSI, as one of the partners of the Third Generation Partnership Project (3GPP), has played a key role in the development of IMS. The importance of IMS to ETSI can further be seen in ETSI TISPAN's choice to place 3GPP IMS at the heart of their Next Generation Network (NGN) standards and by creating a technical committee dedicated to IMS network testing, named TC INT (IMS Network Testing).

ETSI now plans to use these resources in order to further enhance the interoperability of IMS.
The purposes of this event are:

  • To enable participants to assess the level of interoperability of IMS implementations and IMS-based applications.
  • To improve the quality of 3GPP IMS specifications, by detecting any interoperability issues.
  • To ease the introduction of IMS systems, by providing the means to solve interoperability problems before widespread deployment.

The event is open to both IMS equipment vendors and operators, as well as ETSI members and non-members.

In addition, vendors will have the opportunity to show selected demonstrations of the latest IMS services and applications like rich communication services (RCS), also potentially involving mobile devices, as well as IMS testing tools.

The ETSI IMS interoperability event 2 has been held in Bled, Slovenia from November 10th to 14th 2008 at Hotel Golf. The Plugtests assessed the interoperability as well as conformance of IMS core networks (composed of P/I/S-CSCF, IBCF, AS, DNS and HSS) which are implemented on the basis of ETSI ES 283 003 (V1.8.0) [3GPP TS 24.229 Release 7 (Version 7.2.0), modified]. The tests executed at the event were related to basic IMS call functionality, messaging and roaming and were taken from the ETSI IMS NNI interoperability test specification ETSI TS 186 011-2 Version 2.1.8[1].It is important to remember that the main goal of this IMS plugtest has been to assess the base specification of IMS core networks, i.e., not the quality of IMS core network implementations. Therefore, the results are presented in this report purely from a test specification point of view, i.e., they are not related to the participating IMS vendors.

Six IMS core network vendors participated at this event. During the event 410 of 1110 potential tests were executed. Overall results show a very high level of interoperability (82%) of IMS core networks but a lower level of overall conformance to the 3GPP base standard (51 %) in the tests executed. Also note that 29% of all potential tests could not be executed due to issues outside of the IMS core networks, e.g., issues with remote connections and clarity of event configuration information, as well as lack of the support for a feature by a participating IMS core network.

The main interoperability issues encountered were related to call hold/resume functionality, roaming scenarios for basic call and the use of AS in roaming scenarios. Most issues encountered in conformance assessment where related to handling of header tokenization for topology hiding, handling of roaming scenarios (with and without AS involvement), as well as use of P-Charging-Vector and P-Asserted-Identity headers in various SIP requests and responses.

Number of participants
32 participants attended from 14 different companies.