When you use an extension to register a SIP endpoint to Session Manager and an H.323 endpoint to Communication Manager, an incoming call to that extension rings at both the endpoints. The user can answer the call either at the H.323 endpoint or at the SIP endpoint. Calls appear through simulated bridged appearances (SBA) on the other endpoint. You can hand off a call to another endpoint through SBAs or an extend-call button. You can use the following features with a dual-registered extension:

You can create the extension of H.323 type by using System Manager. You can reassign the same extension as SIP by using the off-pbx-telephone station-mapping screen in Communication Manager SAT.

The following endpoints support SIP and H.323 dual registration: