Showing results for 
Search instead for 
Did you mean: 

Cisco VCS Lync gateway communication with Microsoft Lync 2013 Edge - Lync clients calling via an Edge server

Dear community, 


After a successful VCS Lync Gateway B2BUA with Microsoft FEP deployment for Cisco video to MS Lync 2013 client interoperability I am experiencing the following problem / lack of information in the deployment guide. 

I want to enable MS Lync clients on the Internet to be able to call Cisco TP endpoints and Jabber clients on the internal network through MS Lync Edge. 

The guide details this implementation with VCS Expressway TURN services/capabilities, but my goal is not to use VCS Expressway in the media path, but only to use Microsoft Lync Edge server. 

The guide states:

"To enable call connectivity with Lync clients calling via an Edge server, the B2BUA needs to have TURN services properly configured to point to a VCS Expressway with TURN enabled."

Is this mandatory ? 

In the media path diagrams, two options are given for a media path of a Lync client calling via a MS Lync Edge server:

  • One media path is through the MS Edge server
  • Another media path is through the VCS Expressway

My goal is to only enable and use one path - through the MS Edge Server. 

What I am missing in the guide is the precise information, how the VCS Lync Gateway B2BUA communicates with the MS Lync Edge server ? 

In the VCS IP Port Usage for Firewall Traversal Deployment document, it only states that port 3478 UDP outbound needs to be open from the Lync gateway VCS to the MS Lync Edge. Is this true, is it only one TURN UDP port ?

The MS Edge server has two interfaces, internal facing and Internet facing.

On the internal facing interface MS Lync Edge has 1 IP address on the external Internet facing interface it has 3 public IP addresses.

For example:

  • .34 for Access
  • .35 for Web Conferencing and 
  • .36 for A/V

To which of these IPs, is the VCS Lync gateway trying to establish a session ?

What are the source ports on the VCS Lync gateway for this session ? 

Is UDP 3478 the only destination port towards MS Lync Edge ?

Are connections established only in the direction VCS Lync gateway to MS Edge ?

How does media flow through these ports and on which ports ?

Can I NAT/PAT the VCS Lync Gateway source IP address and port when establishing a connection to the MS Lync Edge from the VCS Lync Gateway ?

Can I NAT/PAT the MS Lync Edge destination IP address when establishing a connection to the MS Lync Edge from the VCS Lync Gateway ?


Thank you and best regards,




Thanks a lot for your answer. I think there is no way to put the services outside our LAN because of Client access rights.

I thought there would be a way to proxy the turn connection.

So I try to talk with the network team or a partner.


Thank you so much for great help.

Hello Mihail,

You have added to your diagram additional connectivity between VCSExresway and LYNC Edge Server comparing to  picture from Marco.

Why is it needed and how is the media flow for call from LYNC client registered to EDGE Server to Cisco Endpoint registered Cisco VCS?

Marco has also 3478 outging port from VCS GW to Edge Server but i your diagram you have used media range from VCS GW to Edge Server.

What configuration has to be done on VCS Expressway and EDGE Server please?

Thanks a lot,


Recognize Your Peers
Content for Community-Ad