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Community Member

VCS Expressway and Endpoint DNS Registration

Hi all,


I have installed and configured a Cisco VCS Expressway on DMZ zone. I have installed on the same Zone two Endpoint ( SX20).

I can make an H323 external call from Endpoint to through the VCSE with success. 


Now , for the external incoming calls, i have the following question :

1- My domain is   for ex  :

2- my public ip address that used by VCSE ( NAT on the Firewall is : for ex :

3- the  First SX20 H323ID is   :     , SIP URI :

4- The Second SX20 H323id is :  , SIP URI  :


My question is how from external can i call  the both SX20 ? and in the DNS Server how can i configure the both Endpoint to be resolved correctly ?


Thanks in advance






VIP Super Bronze

Both the SX20 endpoints would

Both the SX20 endpoints would be registered to your VCS Expressway, and you would have DNS SRV records for your domain ( that point to your Expressway.  All incoming external calls would then be routed via the Expressway to connect to either of the two endpoints.

This has been asked many times in the forums, a search pulled up the following for example.


The VCS Basic Deployment Guide, appendix 2, is also a good resource and provides examples.


As well as the following document that just goes over DNS SRV records for the VCS.


Community Member

Hello Patrick, Thank you very

Hello Patrick,


Thank you very much for the answer. it was very useful for me


I configured the DNS SRV record , and now i can call from external endpoint (B2B)  to the internal endpoint ( ).

The call is activated , but i cant not receive audio and video in the both Endpoint !

I woul ask if there is any specifical configuration to do on the VCS Expressway to permit the Video CALL to be routed through the VCSEXpressway ( including Signaling and Media).


PS : the VCS Expressway is installed with the Endpoint on the DMZ , and  we configured a public IP address with nat to the VCS Expressway.


Thank in advance




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