Cisco Phone automatically unregister and register when ISDN call connected

[Debabrata Majhi]

HI all

We have one CUCM cluster 11.5.Now we are wanted to configure a branch office over S2S tunnel.Phone is registering and also internal Extention to Extention call is happening.But when ISDN call is happening the phone automatically disconnected after 5 sec and there is no sound and observe that phone is reregistering.We are using 4321 routers in branch and ISDN PRI E1.

Note:We have registered one phone in HO and when we are calling to any PSTN through Branch office same router and ISDN line everything is working fine.

Please help

[R0g22]

You need to take a trace on UCM to see why is the phone getting unregistered. Do you see any WAN link flaps on the remote router ?

[Debabrata Majhi]

Hi,

Sorry for delay response .Can you please let me know how to check the ISDN/PRI connection.I want to troubleshoot some debug command .

[R0g22]

You can do a "show logg" which might show you some buffered syslogs. If you use IP SLA for monitoring, you might see the logs for that as well.

[Abhay Singh Reyal]

Now here we have to isolate if the issue is due to network or not. In order to know what exactly is causing the trouble I would suggest to collect PCAP from the phone as well in addition to CUCM traces [App and sys log] as advised by Nipun. Once you are done collecting the traces and PCAP provide below info and post it here
- MAC Address of the phone
- IP Address of CUCM

Regards
Abhay