Friday, October 9, 2009

Cisco/Linksys SPA942 & SPA962 Anonymous Caller ID issue

This may be a common problem across all SPA devices from Cisco/Linksys but I have only tested with the SPA942/962 IP phones. For most users this would not even be an issue.

The problem is the way that the SPA deals with anonymous calls. Instead of passing the actual "anonymous" caller id received from the carrier (or gateway) it transforms it to "Anonymous Caller" which may have been a nice touch by one of their engineers to give it a nice looking appearance but it truly messes things up in a scenario where a multi-tenant phone system is used.

In one of deployments we had configured FreePBX to handle three different companies. We didn't do anything special with FreePBX except change the Caller ID prefix for each companies incoming lines. eg. Company A would receive calls with the caller id "A:XYZ Comp <1234567890>"

All this worked great and the receptionist knew how to answer the calls for the different companies. This unfortunately didn't work with anonymous calls. So instead of displaying "A:anonymous" it displayed "Anonymous Caller" - and the receptionist had to no clue for which company the call was for.

To determine that this was truly was a problem with the SPA phones we tested using the following:

1. x-lite - showed the correct caller id for anonymous with the company prefix
2. snom phone - also worked
3. Even a GXP2000 from Grandstream worked - these phones have other issues but the caller id worked

Tried getting this resolved with Cisco - but didn't get far on their public community board.

I am not a Cisco partner so I can't submit a bug report

I did submit as much info to their site as i had time for.

I didn't have time to continue with the additional requests for more info.

At this point I think submitted enough info to reproduce the problem and we had already resolved the problem with an an Asterisk solution - we completely changed all the anonymous calls to "Unknown" before they hit SPA phones.

Just putting this out for anyone who may run into the same issue.


  1. I've the same problem with our SPA525G phones.

    Can you tell me how you changed all anonymous calls to unknown?

  2. I too had the same problem and could not find a fix anywhere, it took me sometime and playing around but I found the fix. The problem is the default setting on the Cisco phone. I have the SPA504G I'm sure this will work on all SPA.

    Login to the Cisco phones Configuration Utility as admin and Advanced. Go to the “SIP” tab and look for “Display Anonymous From Header:” it will be set as “NO”, change it to “Yes” and submit changes.

    Now anonymous calls should display the queues prefix.