(gdb) bt
#0  0x08068235 in clone_variables (original=0x81d85f8, clone=0x815df80)
    at channel.c:2826
#1  0x08068a69 in ast_do_masquerade (original=0x81d85f8) at channel.c:2982
#2  0x08064a60 in ast_read (chan=0x81d85f8) at channel.c:1777
#3  0x08069885 in ast_generic_bridge (c0=0x81d85f8, c1=0x81de7e0, 
    config=0xb723fe30, fo=0xb723f9ac, rc=0xb723f9a8, toms=-1) at channel.c:3233
#4  0x0806ab5c in ast_channel_bridge (c0=0x81d85f8, c1=0x81de7e0, 
    config=0xb723fe30, fo=0xb723f9ac, rc=0xb723f9a8) at channel.c:3494
#5  0xb7b2ead9 in ast_bridge_call (chan=0x81d85f8, peer=0x81de7e0, 
    config=0xb723fe30) at res_features.c:1312
#6  0xb753393d in dial_exec_full (chan=0x81d85f8, data=0xb7244700, 
    peerflags=0xb72404d4) at app_dial.c:1525
#7  0xb7533c25 in dial_exec (chan=0x81d85f8, data=0xb7244700)
    at app_dial.c:1565
#8  0x08089bdc in pbx_exec (c=0x81d85f8, app=0x819cce0, data=0xb7244700, 
    newstack=1) at pbx.c:565
#9  0x0808d80c in pbx_extension_helper (c=0x81d85f8, con=0x0, 
    context=0x81d8748 "agentcall", exten=0x81d883c "511", priority=10, 
    label=0x0, callerid=0x0, action=1) at pbx.c:1703
#10 0x0808eca2 in ast_spawn_extension (c=0x81d85f8, 
    context=0x81d8748 "agentcall", exten=0x81d883c "511", priority=10, 
    callerid=0x0) at pbx.c:2236
#11 0x0808f1f4 in __ast_pbx_run (c=0x81d85f8) at pbx.c:2302
---Type <return> to continue, or q <return> to quit---
#12 0x080900f8 in pbx_thread (data=0x81d85f8) at pbx.c:2523
#13 0xb7eedb63 in start_thread () from /lib/tls/libpthread.so.0
#14 0xb7de818a in clone () from /lib/tls/libc.so.6