Problem using CAMP

[mt6322]

On a Siemens/Rolm 9751 Model 10, what could be the problem when users could no longer CAMP to another extension. This feature used to work for everyone with a display phone, but now when you press CAMP while the other phone is ringing you will hear a busy signal.

Please help to troubleshoot this problem. Thank you

 

[mt6322]

I tried camping on a busy extension ans it works. But the problem is when you try to leave a CALL me message reminder on phone with a display. As usual, users call an extension with a display. If they do not answer, while the phone is still ringing, the user will press CAMP. At this point, you will hear a busy signal. This feature used to work so I do not know what could have caused this problem. Please help. Thanks.