Over the past year we have seen multiple issues with NET VX1800 deployed in Hybrid Gateway mode - Gateway + Communication Server 2007 R2 (CS)\LYNC Server 2010 (LS) Mediation Server (MS). Here I am going to talk about one such issue.
Symptoms - Unable to make calls outbound from CS\LS to PSTN using NET VX1800, Unable to parse through a DTMF driven IVR on calls through VX 1800.
Microsoft's Unified Communication Open Interoperability Program lists all the gateways supported. VX1800 is supported only in Basic Mode and not Hybrid Mode.
In the cases we have worked on so far with NET working in Hybrid Mode, we have seen that VX1800 has challenges recognizing DTMF when transmitted using RFC 2833. A single DTMF event is sent by CS\LS is at times read as multiple events depending on state of the call.
These issues first surfaced in Q1 2010. NET is aware of this issue and currently working on fixing this. For more information please contact NET.
If you need further technical details on this issue please contact Microsoft Support.
In the cases we have worked on, our customers ended up introducing the MS to sit between CS\LS Front End servers and run the NET VX 1800 in Basic Mode.