#0  0x007af39c in pthread_mutex_lock () from /lib/libpthread.so.0
#1  0x080d63e7 in ast_rtp_read (rtp=0xb7d239b8) at /home/src/asterisk/asterisk-1.4.21.2/include/asterisk/lock.h:755
#2  0x00d534a3 in sip_read (ast=0xb7d0f688) at chan_sip.c:4367
#3  0x080858a3 in __ast_read (chan=0xb7d0f688, dropaudio=0) at channel.c:2071
#4  0x0808650c in ast_waitfordigit_full (c=0xb7d0f688, ms=83, audiofd=-1, cmdfd=-1) at channel.c:2348
#5  0x08086868 in ast_waitfordigit (c=0xb7d0f688, ms=100) at channel.c:1791
#6  0x003ab476 in common_exec (chan=0xb7d0f688, flags=0xb756ae88, volfactor=0, fd=0, mygroup=0xb7569e44 "3647", spec=0x0, 
    exten=0x0, context=0x0) at app_chanspy.c:527
#7  0x003ac405 in chanspy_exec (chan=0xb7d0f688, data=0xb756cf08) at app_chanspy.c:740
#8  0x080caa8b in pbx_extension_helper (c=0xb7d0f688, con=0x0, context=0xb7d0f808 "dialout", exten=0xb7d0f858 "83647", priority=1, 
    label=0x0, callerid=0xb7d039b0 "3399", action=E_SPAWN) at pbx.c:537
#9  0x080cd0d2 in __ast_pbx_run (c=0xb7d0f688) at pbx.c:2317
#10 0x080ce08e in pbx_thread (data=0xb7d0f688) at pbx.c:2636
#11 0x080fc03b in dummy_start (data=0xb7d12780) at utils.c:895
#12 0x007ad46b in start_thread () from /lib/libpthread.so.0
#13 0x00311dbe in clone () from /lib/libc.so.6