cahrens,
Call Party Control (CPC) should still have a Loop Disconnect at the end of the call and if you have a CPC Tester then put it on the line and see.
It has been a long time since I had to deal with POTS lines, but if you look at the timers in the MiVO-250 for IC-CO Disconnect is set to 600ms not 350ms. I believe that the 350ms time frame is for CO-CO Disconnect timer. Of course the timers are shown in hundredths of a second and not thousands of a seconds, but the conversion is pretty simple.
LS/GS (LS) CO-CO Disconnect: A call is disconnected by the system if it detects loss of loop current lasting longer than this timer during trunk-to-trunk calls.
LS/GS (LS) Dialing Disconnect: The connection is dropped if the system detects loss of loop current lasting longer than this timer during dialing.
LS/GS (LS) IC-CO Disconnect: A call is disconnected by the system if it detects loss of loop current (
lasting longer than this timer) during station-to-trunk calls.
So, the CPC would have to drop Loop for more than 600ms before the system would see it as a disconnect and if you are telling them to put it to 350ms then the problem would be with the system not seeing it as a disconnect.
You could also read this article on Sandman.com (RIP):
CPC TroubleshootingThere are also devices you can put on the POTS line to provide a Loop Disconnect as well if you don't want to mess with the timers to find the sweet spot.
Thanks,
TE