We have a DID setup which call directly to each extension. Almost all our extensions have a call waiting feature, so if you are on the line and another call comes in, you see your second line light up and you can pick up the call.

A few extensions only beep 3 times when you get a second call coming in, and you do not see the second line light up. I have scoured through the programming and can't figure out if this is a bug or a feature that needs to get turned off. Any suggestions?

Class of service.

I checked 20-06 and the COS is the same for all extensions.

Do you have bad phones? HAve you checked your call1 and call2 keys to see if they are working?

The Call1 and Call2 keys are working, I swapped a working phone to the non working extension, and the same issue persisted, it has to be a setting for the particular extension.

Compare the setting in 15-02-12 from one that works the way you want, to one that doesn't.

Class of service options for incoming calls (20-09-01) enables a second call path for DIDs.

I would suggest turning that on in every class of service just to see what's going on.

Update: We got the issue resolved, the problem was the phone carrier had setup their own call waiting on the PRI circut and was forwarding the call waiting tone to our PBX instead of letting our PBX handle the calls, as it was normally.

Thank you for all the suggestions!