I have a problem with my UC540 with it hanging onto an incoming call despite the fact that the calling party has terminated the call.
I would call my trunk line from my cell and the autoattendant will answer. If I hang up my cell, and then try back the same trunk immediately, I get a busy signal. I would then have to wait 4mins before I can call the line again.
I tested this with an extension (IP Phone) as well. I called the line and punched in the digits to get to my own extension then hung up on my cell. What I realized is that the extension kept on ringing despite the call being terminated. I would get then get the email notification 4mins after the call terminated indicating a voice mail. The majority of the voice mail message would be a busy signal tone. If I answered the call on the extension this problem would not happen.
I also have a trunk line used for fax. This does not use the auto attendant, but transfers directly to one of my FXS ports. Strange thing is I don't get the problem with this line. To test, I configured the "fax" line to use the auto attendant in the Dial Plan->Incoming settings and I got the same problem described above.
The incoming call lines and the fax line are from different providers.
Has anyone experienced this problem? If so, how did you resolve?