(gdb) bt
#0  0xb7e31f89 in free () from /lib/libc.so.6
#1  0xb7b0187f in __sip_destroy (p=0x81a4738, lockowner=1) at chan_sip.c:2097
#2  0xb7b02541 in sip_destroy (p=0x81a4738) at chan_sip.c:2270
#3  0xb7afe14b in __sip_autodestruct (data=0x81a4738) at chan_sip.c:1332
#4  0x0805706e in ast_sched_runq (con=0x8142348) at sched.c:374
#5  0xb7b2c3e4 in do_monitor (data=0x0) at chan_sip.c:11362
#6  0xb7f9673e in pthread_start_thread () from /lib/libpthread.so.0
#7  0xb7e8a08a in clone () from /lib/libc.so.6
(gdb)