(gdb) backtrace
#0  0xb7fd25ed in pthread_mutex_lock () from /lib/tls/i686/cmov/libpthread.so.0
#1  0xb4f0ca1c in register_verify (p=0x83205b8, sin=0xb4eea780, req=0xb4eea790, uri=0xb4eea9ad "sip:213.204.230.37", ignore=0) at chan_sip.c:5017
#2  0xb4f08b84 in handle_request (p=0x83205b8, req=0xb4eea790, sin=0xb4eea780, recount=0x0, nounlock=0xb4eea718) at chan_sip.c:7843
#3  0xb4f03fef in sipsock_read (id=0x810d448, fd=10, events=1, ignore=0x0) at chan_sip.c:7941
#4  0x08052cc0 in ast_io_wait (ioc=0x8146870, howlong=0) at io.c:267
#5  0xb4efe58b in do_monitor (data=0x0) at chan_sip.c:8088
#6  0xb7fd0ae0 in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0xb7ed289a in clone () from /lib/tls/i686/cmov/libc.so.6