[Freeswitch-users] The transferred call is not hanged up.

I have met the non-hanged up call after being transferred. The following is the test scenario. 1. A makes a call to B 2. B answers the call of A and holds the call of A. 3. B makes a call to C and transfers the call of A to C before C answers the call of B. 4. A hangs up the call before C answers the call of A. In this state, C's phone is ringing endless. Why is not the channel of C hanged up? Thanks for reading my mail. Sangwoo Jin.