The Error on 7920 phone when there is an MWI:'External call unknown

[cscarindam14]

Hi All,

Here is the problem scenario.

The IPT installation was running fine with 7960 and 7920 and ATA devices installed to a Callmanager Express 4.1. Later we needed more wireless phones, so ordered the new 7921 phones as 7920 phones are no loger in market. In order to make the 7921 phones work we upgraded the IOS in 2851 router from 12.3(11)T8 to 12.4(15)T1.

The 7921 phones are now working fine, but we have trouble with the 7920 phones. Everytime there is MWI, an error message pops up on the screen " External call unknown". To get rid of the message we need to remove the battery and reset the phones. Next time MWI appears, again the same error message pops up.

I am attaching the picture of the error message herewith. Any help would be appreciated.

[htarra]

I believe that the problem is likely with the unity call handler transfer through CCM and not in the

gateway as the caller-id if it's available can only be provided in the setup message on initial call setup on ISDN.

I found the DDTS CSCsi02523 whose issue is similar.

[cscarindam14]

Hello,

Thanks for your reply. We have upgraded the firmware for the 7920 phones and problem seems to be resolved.

Rgds,

Arindam