How do I configure Asterisk to detect a "phantom"

Hi,

I was using XLite A (extension 100) to call XLite B (extension 101). For some reasons, XLite A crashed but XLite B was still showing the call was still active.

How can I configure Asterisk to detect this and clean up the call? Or is there anything I can do to detect this at somewhere and disconnect the phantom call at XLite B’s side?

Many thanks