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IP phone registration

Hi  there,

I got a little bit confuse regarding the phone registration to the CUCM.

Here is the senario.

There are 2 companys, A and B both have CUCM, there is a direct link at company B to A, I brought a phone from company A and plug in, the port I plugin has company A data vlan and company B voice vlan, I manully changed the ip address, default gateway and TFTP server on the phone that point to company A, but the phone can not register to company A's CUCM, it keeps trying to register but failed.

Once I remove the voice vlan on the port, the phone can register without problem.

what confuse me is what does the voice vlan do to prevent the phone register to company A's CUCM.

Hall of Fame Super Silver

IP phone registration

What version of CUCM is company A? If 8.0 then read up on security by default, you will need to perform factory reset to get it registered.

On the flip side what is the phone status saying? Is it getting IP address and proper TFTP? Is it defined on cluster B or are you using auto registration?


Community Member

IP phone registration

Hi          Chris,

Both CUCMs are version 7.

on the phone screen it shows registering, then after a while, it appears again.

I manually defined the ip address and TFTP server and the phone is not configured in cluster B.

I need the phone register to cluster A to do the testing and the phone was registered to cluster A.



IP phone registration

You can take a pacp from the switchport where the phone is connected and that pcap will help you check the signalling and figure out why it doesn't register.


Posted by WebUser Asad Raza from Cisco Support Community App

Community Member

Re: IP phone registration

Check the network reachability from company b voice plan to company A CUCM

Your data vlan is reachable by company A CUCM dats y its registering

plz check and let us know

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