Hi all,

Just a question. We're trying to get our Lync integrated with a Samsung OfficeServ as a PSTN Gateway. The scenario is as follows:

* Mediation / Lync Server Interal IP: 192.168.0.68

* Samsung PSTN Gateway IP: 192.168.1.240

* Calls from Lync to extensions on the Samsung PABX (Or, outside lines) FAIL with "Gateway side Media negotiation failed" and "SDP Exchange already failed before SetAnswer: Invalid media"

* Calls from Samsung PABX Extensions (or, transferred from outside) work OK.

We've tried things such as bypass media, refer control, etc, all with no luck. We've done a Wireshark and have established that Lync is requesting g.711 ulaw/alaw , of which the Samsung device supports both. 

Even more frustrating is that calls work from Samsung to Lync, but not the inverse.

I have attached the following pastebin's to Lync logging dumps of each call. Unfortunately I don't have access to the wireshark dumps at the moment. One thing we did notice about the wireshark dumps is that there was no 'Ring' packets in the Lync to Samsung, yet the phone actually rang.

Log (Lync to Samsung): http://pastebin.com/51KNhqch

Log (Samsung to Lync): http://pastebin.com/sxXbX78F

Does anyone have any pointers? We are really keen to get this working. Has anyone had a similar problem? Has anyone had luck integrating with a Samsung Officeserv?

Edit: I should add, that we are using TCP on the trunk, as we were unable to establish it via TLS.

• Edited by JustinAU Thursday, July 19, 2012 12:52 AM

I don't see the Samsung OfficeServ listed here:

http://technet.microsoft.com/en-us/lync/gg131938.aspx

So because this is not a certified solution you are going to be lucky if this works and based on the error message you are seeing I might say you would be very lucky if this were to work. The only suggestion I can make is to consider using an IP gateway from NET, AudioCodes, Dialogic to interface between OfficeServer and Lync. No guarantees this will work either but generally the chances are much higher.

• Proposed as answer by Sharon.ShenMicrosoft contingent staff, Moderator Friday, July 20, 2012 3:05 AM

Just as an update - after setting up an Asterisk PSTN Gateway to rout all outgoing calls to the Samsung PABX, Samsung suggested we give it another go with their PSTN gateway (excluding Asterisk) as they had done some setting changes forcing the Samsung to g.711a/law, and then it has suddnely started working through the Samsung gateway. 

We're not sure if that's what fixed it though, as we're certain we did try that originally. It might also have been something in the Lync end we changed that caused it to start working too. Someone on another forum suggested 'Early Offer' as well.

Nonetheless, it seems to be all working now.

Thanks everyone for your input.

• Marked as answer by JustinAU Friday, July 20, 2012 3:24 AM