IP phones cant receive external Calls.

[acrobat2012]

Hi friends,

Could any one give guidance to solve this issue,

I am using CUCM 6.1,everything was fine.suddenly today some of the IP phones can not receive any external calls.It can receive and dial only internal calls.If dial these phones, busy tone is appearing.Just i tried to reconfigured those IP phones, it result same issue.Also i tried to configured new IP phones it gives same problem.Other phones can able to receive or dial external calls.I checked in the gateways,all the E1's are up and everything is registered with the call manager.
what would be the issue, should i check in my call manager???Is it problem in the E1's or in CUCM??
Please anyone guide me to solve this issue.

Reg
AZ.

 

[trvlr1]

Is calling search space etc all the same on a working and a non working phone? You will need to do a side by side comparisson between the two to see if you can see any differences.

 

[hanluc6933]

Is it possible this is a telcove issue and you lost part of your DID range?

The great use of life is to spend it for something that outlasts it. ~William James

 

[pndscm]

Check the CSS on the incoming Gateways. Be sure it includes the partition of the phones that can't get incoming external calls.