(gdb) bt full
#0  0xb76c3e1b in handle_transfer_button (sub=0x0) at chan_skinny.c:4124
        l = (struct skinny_line *) 0xb703a18c
        d = (struct skinny_device *) 0xb703a218
        newsub = (struct skinny_subchannel *) 0x84113d8
        c = (struct ast_channel *) 0x0
        t = 0
        __PRETTY_FUNCTION__ = "handle_transfer_button"
        __FUNCTION__ = "handle_transfer_button"
#1  0xb76c99e2 in handle_soft_key_event_message (req=0x85ca940, s=0x85e0a00) at chan_skinny.c:5466
        d = (struct skinny_device *) 0x8417580
        l = (struct skinny_line *) 0x84113d8
        sub = (struct skinny_subchannel *) 0x0
        c = (struct ast_channel *) 0x8178a87
        t = 3070471056
        event = 4
        instance = 1
        callreference = 3
        __PRETTY_FUNCTION__ = "handle_soft_key_event_message"
        __FUNCTION__ = "handle_soft_key_event_message"
#2  0xb76cb750 in handle_message (req=0x85ca940, s=0x85e0a00) at chan_skinny.c:5869
        res = 0
        __PRETTY_FUNCTION__ = "handle_message"
#3  0xb76cc872 in skinny_session (data=0x85e0a00) at chan_skinny.c:6038
        res = 20
        req = (struct skinny_req *) 0x85ca940
        s = (struct skinnysession *) 0x85e0a00
        __PRETTY_FUNCTION__ = "skinny_session"
#4  0x08179af5 in dummy_start (data=0x85df6d0) at utils.c:968
        __cancel_buf = {__cancel_jmp_buf = {{__cancel_jmp_buf = {-1213968396, 0, 4001536, -1224498248, -196836940, -600721718}, __mask_was_saved = 0}}, __pad = {0xb703a480, 0x0, 0x0, 0x0}}
        __cancel_routine = (void (*)(void *)) 0x80767ea <ast_unregister_thread>
        __cancel_arg = (void *) 0xb703ab90
        not_first_call = 0
        ret = (void *) 0x0
        a = {start_routine = 0xb76cc781 <skinny_session>, data = 0x85e0a00, name = 0x85c8328 "skinny_session       started at [ 6085] chan_skinny.c accept_thread()"}
        lock_info = (struct thr_lock_info *) 0x85f4160
        mutex_attr = {__size = "\001\000\000", __align = 1}
        __PRETTY_FUNCTION__ = "dummy_start"
#5  0xb7a36315 in start_thread () from /lib/i686/libpthread.so.0
No symbol table info available.
#6  0xb7cb525e in clone () from /lib/i686/libc.so.6
No symbol table info available.