I ran into another problem with my UC520 set-up today. External PSTN call comes in through the FXO ports successfully but when the call is completed and the caller hangs-up, the UC520 does not seem to release the PSTN line (i.e the LED on the FXO remains "on") and new external call attempt on that FXO gets a "busy" tone. I have to manually unplug the PSTN and plug it back into the UC520 for the line to become usable again. Is there a way to resolve this problem?
Thanks in advance for your help as always.