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When IP Phones are registered to the MGCP gateway and are in SRST mode, calls are successful, but once they are returned to Cisco CallManager, SRST active calls from IP Phones to PSTN through BRI still show active in show voice call

Core Issue

If an IP Phone is registered to the Media Gateway Control Protocol (MGCP) gateway while in Survivable Remote Site Telephony (SRST) mode, calls are successful. But, when the connection is restored to the Cisco CallManager, the gateway registers to Cisco CallManager before the IP Phone and the Basic Rate Interface (BRI) is backhauled. If a call is made from the SRST IP Phone to the gateway, the call gets stuck.


A workaround for this issue is to reload the gateway router.

In order to resolve this issue, upgrade the software on the gateway to the appropriate version 12.4(12.8), 12.4(9.12)T, 12.4(9)T02, 12.4(10b), 12.4(12a).

You can download the relevant Cisco IOS  software release from the Software Center.

Refer to these documents for more information about the MGCP gateway: