(gdb) bt
#0  0x080838f0 in pbx_substitute_variables_helper_full (c=0x0, headp=0x3c8, cp1=0x819f717 "${GROUP_SUPPORT}&SIP/128", cp2=0xbfa2dbb0 "", count=255)
    at strings.h:151
#1  0x08083d11 in pbx_substitute_variables_helper (c=0xe, cp1=0x47 <Address 0x47 out of bounds>, cp2=0x47 <Address 0x47 out of bounds>, count=71)
    at pbx.c:1560
#2  0xb78a1f23 in pbx_load_module () at pbx_config.c:1632
#3  0xb789f0c7 in load_module () at pbx_config.c:1791
#4  0x0805bcf3 in __load_resource (resource_name=0x815b70b "pbx_config.so", cfg=0x21) at loader.c:413
#5  0x0805b4cb in load_modules (preload_only=-1079845072) at loader.c:553
#6  0x080b3613 in main (argc=-1079844464, argv=0xbfa2e354) at asterisk.c:2158