Hello,

Has anyone had luck with configuring a single mediation server with both an external (internet) SIP trunk provider and with internal SIP to a phone system at the same time?

We have a survivable branch server at a remote site. It is currently integrated with a Mitel 3300 phone system via SIP trunking and all is working as expected. Currently we have 2 NICs in the Survivable Branch Server as following:

NIC1 - on server LAN

NIC2 - on Phone LAN - designated as PSTN.

We are looking to implement SIP trunk provider for certain external calls. I know how I would do that via the dial/user policies in Lync, but can't wrap my head around the networking part of it. I've added the SIP trunk provider info in the Lync topology and calls are connecting but I hear no sound in either direction.

We captured a packet trace and it appears that the IP in SDP header passed by the Mediation server is internal IP on the PSTN network. That's fine since we want that to be passed to the Mitel 3300. However, since it is a private IP it is not resolvable from the internet and thus it doesn't work with the external SIP provider.

Anyone had any luck with configuring something like this? Any way we can add another IP for the external SIP provider communication? OR would I have to spin up another mediation server specifically dedicated for the external SIP provider communication?

Cheers,

Max

I

Hi,

are both MITEL and PSTN use NIC2? if so, i'd recommend that you add another interface and get the PSTN Trunk configure in to that. you don't need another Mediation server.

Hey Thamara,

The NIC2 on the mediation server is dedicated to the phone lan over which we connect to the MITEL via a SIP trunk. We are not looking to change this config as is currently being used.

I can easily add another IP for the external SIP, but I'm not sure how to specify it in Topology builder (the field only allows one IP to be dedicated for PSTN, and we already have the NIC2 IP defined there). As far as I know the IP specified as the PSTN IP in topology builder is the one advertised in the SDP.

are we talking about Lync Server 2013 here? if so, you can configure multiple Trunks in topology and configure routes to send calls out.

Unfortunately it is Lync 2010.  I'm still poking around and am trying to figure out if SIP translations on a firewall level could assist with this, but so far no luck. I'll be adding another interface on wednesday and will keep you posted.

To add to this - it appears that Mediation Servers can't be NAT-ed which is why I may have to add an interface that is directly externally exposed.( http://social.technet.microsoft.com/Forums/lync/en-US/847782f4-59b8-4fea-afff-8c42bd0668e1/sip-and-nat-wrong-contact-address-in-the-sip-packets ). This might have something to do with why the mediation server in Lync 2010 doesn't seem to support more than one PSTN IP address (which is what get's advertised in the SDP part of the handshake). 

• Edited by Maxim M 17 hours 13 minutes ago