(gdb) bt
#0  0xfeb6598c in strlen () from /lib/libc.so.1
#1  0xfebc0432 in _ndoprnt () from /lib/libc.so.1
#2  0xfebc3567 in vsnprintf () from /lib/libc.so.1
#3  0x081251e9 in __ast_str_helper (buf=0x80407d4, max_len=1024, append=0, fmt=0x8171450 "Cannot find extension '%s' in context '%s'\n", ap=0x8040844 "?O\004\b") at utils.c:1746
#4  0x080cfb2c in ast_log (level=2, file=0x815818d "pbx.c", line=0, function=0x814c205 "pbx_extension_helper", fmt=0x80407d4 "\b\206\032\b??CJ?m\b") at /export/home/yrashk/Downloads/asterisk-1.6.1.1/include/asterisk/strings.h:631
#5  0x080e8856 in pbx_extension_helper (c=0x0, con=0x82d7d50, context=0x0, exten=0x8044fb0 "_0", priority=0, label=0x82c7a8b "", callerid=0x0, action=E_MATCHMORE, found=0x0, combined_find_spawn=0) at pbx.c:3226
#6  0x080e8a68 in ast_findlabel_extension2 (c=0x0, con=0x0, exten=0x8044fb0 "_0", label=0x82c7a8b "", callerid=0x0) at pbx.c:3633
#7  0xfd6f67a1 in pbx_load_module () at pbx_config.c:1510
#8  0xfd6f6aba in load_module () at pbx_config.c:1722
#9  0x080cd668 in load_resource (resource_name=0x81d6ae8 "pbx_config.so", global_symbols_only=0) at loader.c:681
#10 0x080cddf9 in load_modules (preload_only=0) at loader.c:884
#11 0x0807c9e6 in main (argc=134511588, argv=0x8047dd0) at asterisk.c:3455