Tuesday, February 21, 2012 1:29 PM
A new sip-provider i am testing tells me that they receive no codec negotiation from our mediation server. He tells me to specify which codec i want to use. After my knowledge i am not able to change this setting in Lync since it will automatically offer both PCMU & PCMA and the provider can pick what they want. Is this or is it not correct?
I also have 3 other sip-trunks from other providers which is working. I try to tell our new provider but he won't listen.
Some input on this issue?
Best Regards - Espen
Tuesday, February 21, 2012 11:46 PM
Is this SIP trunk Lync Certified?
If you are not familiar with Lync I highly recommend you go with a Lync Certified SIP Trunk provider. (Actually whether you are familiar or not ;-)
Here is a list:
Certified does not mean expensive. Intelepeer, for example, can fit very small businesses.
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Thursday, February 23, 2012 7:20 AMModerator
Agree with Matt,the certified SIP trunk provider is strongly recommended.
Lync Server 2010 uses standards and published interfaces to interoperate with existing infrastructure. It supports both gateway and SIP options (such as SIP trunking) for interconnection to IP PBX systems and the PSTN networks, so that you can migrate users to Enterprise Voice over time, while minimizing disruption. Lync Server supports traditional codecs such as G.711, G.722, and G.723.1 for interoperability with traditional VoIP solutions.Thus,if you are using the certified SIP trunking it can negotiate with Lync like a charm;otherwise you need a certified gateway put in the middle of SIP trunking and your mediation server to get them talk with each other.
There are some discussions in another thread talking about the codec negotiation between SIP trunking and Mediation server for your reference.
TechNet Community Support
Monday, February 27, 2012 2:16 AM
Lync Mediation server only negotiate with G711 PCMA and PCMU. if your service provider must support and negotiate on this. run a wireshark on mediation server and confirm once the change is made from the providers side.
Thamara. MCTS, MCITP Ent Admin, Specialized in U.C Voice OCS 2007 R2 Z-Hire -- Automate IT Account creation process ( AD / Exchange / Lync )
Monday, February 27, 2012 9:17 AM
Install Wireshark on your Mediation server and run trace when you call test number that this SIP Trunk provider issued to you.
Filter out only UDP traffic, then TCP on next test call (or host their_IP_address, whatever you're used to)
If they're not MS certified, it's very likely they send SIP INVITE using UDP, like classic SIP/VoIP providers do.
Mediation server talks only TCP.
I used to scratch my head for weeks why this was not working with uncertified VoIP provider.
Wednesday, March 28, 2012 7:56 AM
Thanks for all the good input on this issue. I really appreciate it.
The sip-trunk i am testing is suppose to be certified even if the list isn't updated on the Microsoft website. The trunk provider i am talking about is Ventelo Norway.
I have static routes on the network card of my mediation-server and no gateway.
In the pdf document from Ventelo they told me that i only should use one ip address against their trunk.
I started a wireshark and found out that they used one address for sip-signaling and another ip address for media. I added a static route for the media ip and now i get audio both ways.
I talked to Ventelo and they confirmed using one ip for signaling and another for media, as default.
- Edited by Espen André Hansen Wednesday, March 28, 2012 7:58 AM