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7821 phones registering and un registering intermittently

Mohammed Idris

There are around 40, 7821 ip phones at branch location which are registered to central CUCM cluster at HQ. ip phones are registering and unregistering intermittently. there is MPLS link between the locations. What could be the issue?

15 Replies 15

Siva chinap

What is the error message you can able to see on the phone?

Did u verified VLAN information? whethere phone is able to get an IP address?

Try to ping  HQ CUCM from Branch..

What is the error message you can able to see on the phone?

--No idea

Did u verified VLAN information? whethere phone is able to get an IP address?

---Gets an IP address.

Try to ping  HQ CUCM from Branch..

--Ping is ok.

I said it registers and then unregisters and then again registers with the same IP add.

If all phones are unregistering at the same time then that would indicate an unstable network either at the LAN side oe WAN. Please check with your network team to see if WAN is stable?

I agree with Vishal with it being a network issue. 

If a phone misses 3 keep alives(sccp?) it will attempt to register with the next call manager within it's callmanager group.  If it fails to receive 3 keep alives from the last callmanager within the call manager group, it fails over to SRST if SRST is enabled. 


Missed keepalives is usually due to a network problem.  If you run into trouble resolving or locating the network trouble, you can change the keep alive timer from 30(default) to 90 seconds for the Branch phones. 

Phones will need to be reset before the change takes effect.  This can be done with the BAT tool.  I tested this and our phones have **not** automatically reset.


Hope this helps.

Please rate helpful posts.


Hi Mohammed,


Are you resolved the issue, i have the some behavior with 7821.

Tell me know if you have fixed the problem.

attached the log file

Thank's by advance

Not really. I am planning to send somebody to the remote site as its far from city within next 1 week or so to find out what exactly happening with the phones. Mean while if you get any hint please let me know. Thanks.

Ok, i tell you know when i have a news

Hi, did you resolve this issue .

Yes. The issue is resolved. Firewall policies were modified.

I checked and found something strange. Ip phones are shown unregistered in CUCM but actually they are not if you see from the ip phone screen they are not shown as unregistered. If you pick up the hand set those are again shown as registered. Any Idea why its happening? Again this is happening randomly with some of the ip phones.

Try restarting the tomcat service.

Can you confirm the phones DID NOT reboot?

Hi Mohammed Idris,

I know this is quite old thread....

I am facing same exact issue,

In CUCM phone is unregistered, however on phone screen it shows register till the time phone is ideal, once you try to call it shows registering and then registers successfully.

For me this is happening over LAN network, CUCM ver 11

Happening with 78XX and 39XX phones, however 88XX working fine....

If possible can you please let me know if you have fixed your issue or not, if yes request you to share solution.

Deval Tetar

Nadeem Ahmed
Cisco Employee
Cisco Employee

Can you please check the switch logs where phones are connected 2. Secondly can you please pull console from one of the phone and see the events.




nadeem Ahmed

Br, Nadeem Please rate all useful post.
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