How to disconnect soft phone when pstn call disconnects

Hi,
we developed soft phone (cti) using .NET ,when soft phone gets incoming call from pstn its ringing and we can answer the call,but when we disconnect pstn call before its is answered ,soft phone is still in ringing mode it is not disconnected.
please help…

Thanks

Implement SIP CANCEL in the soft phone (you didn’t actually say you were using SIP), or provide logging that proves that the cessation of ringing current is not being detected.

I’m assuming you are not answering prematurely.

Also please use Asterisk Support in future. This is a discussion forum not one for questions.