I am using the Samsung Prostar 816 plus with Starmail set up as an auto attendant. Everything was working perfectly until we switched from POTS to VOIP. Now, the problem that we have is when an incoming call gets transferred to voicemail, the system does not recognize when the caller hangs up. The line remains in an off hook state for the maximum recording time specified and then times out. The same thing happens when an incoming caller hangs up immediately after Starmail answers the call. We get two minutes of air being recorded. The VOIP provider says that they show that the router is releasing the line when the caller hangs up.
There is no problem, however, when the incoming caller is transferred to an extension and the call is answered by a person who then subsequently hangs up. The line is released immediately.
I have the installation and programming manuals of both the Prostar & Starmail, but could not locate anything to solve the problem.