(gdb) bt
#0  0xb79bf24a in sip_scheddestroy (p=0x824a658, ms=32000) at chan_sip.c:2902
#1  0xb79e0ecb in check_auth (p=0x824a658, req=0xb75edf58, username=0x8216468 "726", secret=xxx, md5secret=xxxx, sipmethod=2, uri=0xb75ee185 "sip:ipbx.i.cz:5061",
    reliable=XMIT_UNRELIABLE, ignore=0) at chan_sip.c:10064
#2  0xb79e1931 in register_verify (p=0x824a658, sin=0x828537c, req=0xb75edf58, uri=0xb75ee185 "sip:ipbx.i.cz:5061") at chan_sip.c:10255
#3  0xb7a0730a in handle_request_register (p=0x824a658, req=0xb75edf58, sin=0x828537c, e=0xb75ee185 "sip:ipbx.i.cz:5061") at chan_sip.c:17658
#4  0xb7a08163 in handle_incoming (p=0x824a658, req=0xb75edf58, sin=0x828537c, recount=0xb75ec8cc, nounlock=0xb75ec8c8) at chan_sip.c:17877
#5  0xb7a08c03 in handle_request_do (req=0xb75edf58, sin=0x828537c) at chan_sip.c:18028
#6  0xb79bb19c in _sip_tcp_helper_thread (pvt=0x0, ser=0x8285368) at chan_sip.c:2221
#7  0xb79bac1b in sip_tcp_worker_fn (data=0x8285368) at chan_sip.c:2145
#8  0x08139a02 in ast_make_file_from_fd (data=0x8285368) at tcptls.c:463
#9  0x08146219 in dummy_start (data=0x824c218) at utils.c:870
#10 0xb7c564e2 in start_thread () from /lib/i686/libpthread.so.0
#11 0xb7d3e46e in clone () from /lib/i686/libc.so.6