3rd IMS Plugtests

In 2009 the IMS Plugtest focused on the interoperability of 3GPP IMS Release 7 equipment.
The purposes of this event were:

  • To enable participants to assess the interoperability of core IMS networks with commercial IMS user equipment as well as 3rd party application servers realizing key MMTel services and presence.
  • To assess the quality of IMS core networks and their conformance to IMS specifications, and to provide feedback to standardization. 
  • To ease the introduction of IMS systems into the market place by providing the means to solve interoperability problems before widespread deployment. 

This event has been open to both, IMS equipment vendors and operators, as well as ETSI members and non-members. In addition, an exhibition area enabled vendors to showcase their products.
The third ETSI IMS interoperability event has been held in Lannion, France from October 16th to 23rd 2009 at the Complexe des Ursulines. It was organized with Orange Labs who are supplying the test network infrastructure and the Multi-Service Forum (MSF) as technical partners. 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 TS 124 229/3GPP TS 24.229 (Version 7.14.0).

The main focus was the assessment of the interoperability as well as conformance of IMS core networks (composed of P/I/S-CSCF, IBCF, AS (telephony and presence), DNS and HSS) which are implemented on the basis of ETSI TS 124 229 (V7.14.0) [3GPP TS 24.229 version 7.14.0 Release 7] at their network-to-network interfaces (NNI). The tests executed at the event were related to basic IMS call functionality, messaging, IMS roaming, topology hiding, MMTEL supplementary services, and the presence service and were taken from the ETSI IMS NNI interoperability test specification ETSI TS 186 011-2 Version 2.3.1 which includes 52 interoperability tests.

The second focus was the interoperability of IMS core networks with legacy PSTN networks which are still widely deployed throughout the telecommunications market. The interoperability functionality and the mapping of IMS to ISUP parameters is described in ETSI TS 129 163 version 7.14.0 [3GPP TS 29.163 version 7.14.0 Release 7]. At the event, IMS cores were either connected via their own or and a third party media/signalling gateway to a PSTN network via the CSS#7 E1 interface. The IMS–PSTN test specification used at the event included 21 interoperability tests. 

Eight IMS core network vendors participated at this event. During the event 495 of 2805 potential IMS NNI tests were executed. Overall results show a very high level of interoperability (89%) of IMS core networks but a lower level of overall conformance to the 3GPP base standard (55%) in the tests executed. Also note that 13% of all potential tests could not be executed due to issues outside of the IMS core networks, e.g. lack of the support for a feature by a participating IMS core network. Overall interoperability and conformance results for IMS NNI tests also executed in last year's event showed a significantly higher performance than last year's results. Technical areas that showed interoperability shortcomings during the last IMS Plugtest, e.g. topology hiding, showed a more mature behaviour.

Five IMS core network vendor took the opportunity to prove the interoperability of their systems with the PSTN world. The very high level of interoperability (88%) promises a successful parallel co-existence of PSTN and IMS for the transition period from traditional to next generation networks. It should be noted an interoperability of 100% was observed for basic call tests.