Use this option to set the Ringing Signal End Detection time. If the ringing signal on a line call is
interrupted for longer than this interval, the system assumes ringing has stopped and terminates the call.
Set this option for compatibility with the connected telco or PBX Centrex. If this interval is set to short,
valid ringing will be inadvertently cut off. If too long, the system will leave the call set up even after
ringing has stopped.