Cisco TelePresence Video Communication Server (VCS)

Video Communication Network Calls an H.323 Endpoint from a SIP Endpoint Configuration Example

Document ID: 118875

Updated: Mar 31, 2015

Contributed by Cisco TAC Engineers.



This document describes how to configure a video communication network so you can call an H.323 endpoint from a Session Initiation Protocol (SIP) endpoint with the H.323 endpoint's E.164 number.



Cisco recommends that you have knowledge of Cisco TelePresence Video Communication Server (VCS).

Components Used

The information in this document is based on a Cisco VCS.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


For SIP endpoints and H.323 endpoints to be able to communicate with one another, there must be a Cisco VCS in the call route which interworks the call between the two protocols.

SIP endpoints can only make calls in the form of Uniform Resource Identifiers (URIs) - for example, name@domain. If you do not specify a domain, the SIP endpoint automatically appends its own domain to the number you dial. So if you dial 123 from the SIP endpoint, the search is placed for 123@domain. If your H.323 endpoint is just registered as 123, then the Cisco VCS is not able to locate the alias 123@domain.

The solutions are to either:

  1. Ensure all your endpoints, both H.323 and SIP, register with an alias in the form name@domain.
  2. Create a pre-search transform on the Cisco VCS that strips the @domain portion of the alias for those URIs that are in the form of nnn@domain. Refer to the Dial Plan and Call Processing section of the online help or the Cisco VCS Administrator Guide for information about how to configure transforms.


There is currently no verification procedure available for this configuration


There is currently no specific troubleshooting information available for this configuration.

Updated: Mar 31, 2015
Document ID: 118875