Over the last few weeks I have been doing a bit of research into Avaya and OCS R2 interoperability. When you refer to the OCS Open Interoperability web page you will find Avaya under the supported IP-PBX section. This means Microsoft has tested the interoperability internally and this is not OIP Certified as with other gateways etc. This means Microsoft does support the configuration but the other vendor may not. In saying that Avaya has released some documentation on this interoperability but it has been a while since it was updated.
OCS Enterprise Voice - Avaya interoperability - Direct SIP
Firstly, documentation on this interoperability is hard to find. Avaya have released this document on call routing between the two systems. It is based around using the Avaya SIP Enablement Server version 4.x and OCS R1. This document is about a year and half old which means things have changed since its release but I was unable to find any updated documentation publicly available. One thing about this document is it makes references to Remote Call Control. Its is not applicable to this configuration and is somewhat distracting for it to be in this document.
Avaya did document issues which are listed below:
“On a call between an Avaya phone and an EV client, the EV client is not able to place the call on hold. The microphone and speakers on the EV client are muted, but the call is not actually placed on hold. In contrast, on a call between two EV clients, both EV clients are able to place the call on hold.”
“On a call between an Avaya phone and an EV client, attempts by the EV client to
conference in another Avaya phone or EV client fail” and “On a call between two EV clients, attempts by either EV client to conference in an Avaya phone fail.”
Microsoft have also listed known issues for SES 4.x:
Configuration requires setting "Alternate Route Timer(sec)" value from default of 10 sec to 30 sec. The configuration should show "Alternate Route Timer(sec): 30" in the corresponding SIP signaling group.
When an call is ringing to the Office Communicator user, the caller (either on an Avaya station or a PSTN line routed through the PBX) will not get ring back tone. This issue has been resolved by Avaya with the 5.x software releases.
Quality of Experience reports will not contain information regarding jitter and packet loss.
Comfort noise generation is not supported. As a result, comfort noise is not played on Office Communicator.
ISDN Failover is not supported from an OCS perspective. If the Avaya PBX is being used for PSTN connectivity and multiple T1's are being utilized, an OC client will not retry a call based on a T1 being unavailable. It may be possible to configure the Avaya to not assign outbound calls from OCS to an unavailable T1, but this configuration was not tested.
So while this may have some issues for 4.x it is recommended by Microsoft to use SES 5.x software to get the best results. If planning to use direct SIP I would recommend thoroughly testing before deployment of the service.
An Alternative Solution
Another configuration that would also be possible is to use a Hybrid Gateway from one of the certified gateway vendors http://technet.microsoft.com/en-us/office/ocs/bb735838.aspx that also supports IP-IP GW features. Considering that some of these vendors have completed interoperability testing with Avaya and Microsoft it may present a more flexible solution with fewer issues.
Avaya OCS Interoperability