Cisco ip phone 7811

[Danar Kamal]

Hi

I have 20, 7811 phones all working fine and i added 5 new phones but the 5 new phones they have a problem. The problem is after registering all 5 on my server once they recive a call it would be instantly cut the moment i pick up the phone. 

any reason to why is this happening 

[Ibrahim AlQumairi]

Did the newly added phone have the same configuration that the old ones have, especially the device pool?

[Danar Kamal]

Yes, the configuration of the new phones are the same as the configuration of the old ones.

[Maren Mahoney]

Dialing a number, having the phone ring, and then the call immediately disconnecting upon pickup is a classic symptom of the system being unable to negotiate a codec. 

This is the reason that @Ibrahim AlQumairi asked about the configuration being the same. Codec selection is made through the Region setting on the phone. One of the things configured via Device Pool is the Region used to set up a call.

I hope this helps!

Maren

[Danar Kamal]

Thanks for the clarification, but the configuration for the phones are the same. Any other reason as to why this problem is happening.

[Maren Mahoney]

Okay. So then we'll need some more information - Are you running CUCM or CUCM Express (and what version), or are these registered to Webex? Are the working phones and the new phones co-located or at different locations? If you have CUCM or Webex: How many regions do you have? Device Pools?

Your post said that when the new phones receive a call and pick up, the call drops. Are the inbound calls that are dropping from other internal phones, inbound from the PSTN, or all inbound calls? Can the 5 new phones successfully place a call?

Is there anything else you can think of that is different between the working phones and the 5 new phones?

Maren

[Danar Kamal]

I am running CME on ISR 4321, webex not added i have one device pool and the problem only happens on the new phone

[Maren Mahoney]

There aren't device pools in CUCM Express, so I'm hoping we are talking about the same thing.

First, please do answer the remaining questions I asked so that I can better help.

Second, please configure your router with "debug ccsip messages" and place a call to one of the non-working phones. Capture the debug in a TXT file and attach it to your reply post. Another TXT file with your router config would also be helpful. With that we should be able to determine why the calls are failing.

Maren