Topology: Local phone---VG20-16---AR18-30---R2621---CC&08---opposite phone
The interior of VG20-16 downlink phone can be called. External phone can dial, but internal phone cannot dial.
Check with display vioce vcc channel command on R2621. It is found that uplink channel is occupied and calling source is abnormal. It is possible that there is deadlock. Shut/undo shut the interface of R2621 and CC&08 so that signal channel can be released. Check signal channel again with display vioce vcc channel command. Abnormal calling source disappears and the service recovers.
1. VG phone is one-way reachable, it indicates that the route of the device exists and does not change.
2. R2621 attaches GK server. It is possible that GK is problematic. Check GK and it is not abnormal.
3. VG20-16 under R2621 is one-way reachable. R2621 may be problematic.
4. Check signal channel between R2621 and CC&08. In channel has been occupied. Calling source is abnormal.
5. Release signal channel.