(gdb) bt
#0  ast_extension_match (pattern=0x75f380 "_0.", data=0x402c8714 "01749140769")
    at pbx.c:730
#1  0x00002aaaad53f409 in realtime_switch_common (
    table=0x402c1c9c "extensions", context=0x402c1c90 "TERMINATION", 
    exten=0x402c8714 "01749140769", priority=1, mode=0) at pbx_realtime.c:148
#2  0x00002aaaad53f672 in realtime_exists (chan=0x0, 
    context=0x7c6cc4 "default", exten=0x402c8714 "01749140769", priority=1, 
    callerid=0x402c8620 "13", data=0x758bc9 "TERMINATION@extensions")
    at pbx_realtime.c:164
#3  0x000000000044643c in pbx_find_extension (chan=0x0, bypass=0x0, 
    context=0x7c6cc4 "default", exten=0x402c8714 "01749140769", priority=1, 
    label=0x0, callerid=0x402c8620 "13", action=0, incstack=0x402c80d0, 
    stacklen=0x402c60cc, status=0x402c84dc, swo=0x402c84f0, data=0x402c84e8, 
    foundcontext=0x402c84e0) at pbx.c:959
#4  0x0000000000449034 in pbx_extension_helper (c=0x0, con=0x0, 
    context=0x7c6cc4 "default", exten=0x402c8714 "01749140769", priority=1, 
    label=0x0, callerid=0x402c8620 "13", action=0) at pbx.c:1737
#5  0x000000000044a98e in ast_exists_extension (c=0x0, 
    context=0x7c6cc4 "default", exten=0x402c8714 "01749140769", priority=1, 
    callerid=0x402c8620 "13") at pbx.c:2295
#6  0x00002aaaadb75968 in get_destination (p=0x7c6690, oreq=0x0)
    at chan_sip.c:7007
#7  0x00002aaaadb88145 in handle_request_invite (p=0x7c6690, req=0x402c8c00, 
    debug=0, ignore=0, seqno=1461615180, sin=0x402c8bf0, recount=0x402c8be4, 
---Type <return> to continue, or q <return> to quit---
    e=0x402c902f "sip:01749140769@192.168.254.200") at chan_sip.c:10924
#8  0x00002aaaadb8b654 in handle_request (p=0x7c6690, req=0x402c8c00, 
    sin=0x402c8bf0, recount=0x402c8be4, nounlock=0x402c8be8)
    at chan_sip.c:11714
#9  0x00002aaaadb8c01a in sipsock_read (id=0x770830, fd=16, events=1, 
    ignore=0x0) at chan_sip.c:11860
#10 0x00000000004118a0 in ast_io_wait (ioc=0x771010, howlong=1000) at io.c:284
#11 0x00002aaaadb8c82d in do_monitor (data=0x0) at chan_sip.c:12027
#12 0x00002b811417c09e in start_thread () from /lib64/libpthread.so.0
#13 0x00002b8114d6a4cd in clone () from /lib64/libc.so.6
#14 0x0000000000000000 in ?? ()