Cisco Cisco TelePresence Video Communication Server Expressway

Enabling registrations and calls 

The Cisco VCS platform supports two different signaling protocols: H.323 and SIP. 

The Cisco VCS also supports interworking functionality. Interworking enables calls initiated from one 
signaling protocol to be made to destinations which use the other signaling protocol (i.e. from a SIP 
registered endpoint to a H.323 registered endpoint and vice versa). 

All endpoints which are required to make calls via the Cisco VCS must first be registered to the Cisco 
VCS. 

The registration process (at high level) requires that the endpoint first makes its address (identity) 
known to the Cisco VCS. The Cisco VCS then accepts (or rejects) the registration. After the endpoint 
is successfully registered, the Cisco VCS will attempt to route all signaling messages received for the 
endpoint address (identity) to the endpoint. 

Some endpoints support a single signaling protocol (i.e. H.323 or SIP); some endpoints support dual 
protocol registration (i.e. H.323 and SIP). 

Endpoints registering using H.323 can register the following address types to the Cisco VCS: 

 

H323 ID – for example: 

 

user1 or 

user1@example.com 

 

E.164 number – for example: 

0123456789 

 

Endpoints registering using SIP can register the following address type to the Cisco VCS: 

 

SIP URI – for example: 

 

user1@example.com 

Cisco VCS Deployment Guide: Single Cisco VCS Control – Basic Configuration 

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