(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00007facdd52bec2 in t38_core_rx_ifp_packet (s=0x7fab29e2ebe8, buf=0x7fab29cbb44b "\002", len=1, seq_no=0) at t38_core.c:457
#2  0x00007fad0d20ec95 in generic_fax_exec (chan=0x7facd41bff28, details=0x7fab28d39988, reserved=<value optimized out>, 
    token=<value optimized out>) at res_fax.c:1498
#3  0x00007fad0d210965 in receivefax_exec (chan=0x7facd41bff28, data=<value optimized out>) at res_fax.c:1933
#4  0x000000000051aef4 in pbx_exec (c=0x7facd41bff28, app=0x1793460, 
    data=0x7facc4035100 "/opt/tmp/IProvider/fax/3b2642f7-e41c-487c-b649-849d14b7e0d0.tiff,dfs") at pbx.c:1589
#5  0x00007fad0d88bce2 in handle_exec (chan=0x7facd41bff28, agi=0x7facc2bce4c0, argc=3, argv=0x7facc2bcce60) at res_agi.c:2521
#6  0x00007fad0d88e7a1 in agi_handle_command (chan=0x7facd41bff28, agi=0x7facc2bce4c0, buf=0x7facc40350f0 "EXEC", dead=0) at res_agi.c:3418
#7  0x00007fad0d89035c in launch_asyncagi (chan=0x7facd41bff28, data=<value optimized out>, enhanced=<value optimized out>, dead=0)
    at res_agi.c:1329
#8  launch_script (chan=0x7facd41bff28, data=<value optimized out>, enhanced=<value optimized out>, dead=0) at res_agi.c:1631
#9  agi_exec_full (chan=0x7facd41bff28, data=<value optimized out>, enhanced=<value optimized out>, dead=0) at res_agi.c:3899
#10 0x000000000051aef4 in pbx_exec (c=0x7facd41bff28, app=0x178a720, data=0x7facc2bd0680 "agi:async") at pbx.c:1589
#11 0x0000000000525664 in pbx_extension_helper (c=0x7facd41bff28, con=0x0, context=<value optimized out>, exten=<value optimized out>, 
    priority=3, label=0x0, callerid=0x7facd426dbd0 "Anonymous", action=E_SPAWN, found=0x7facc2bd2cfc, combined_find_spawn=1) at pbx.c:4665
#12 0x000000000052c525 in ast_spawn_extension (c=0x7facd41bff28, args=0x0) at pbx.c:5781
#13 __ast_pbx_run (c=0x7facd41bff28, args=0x0) at pbx.c:6256
#14 0x000000000052dcab in pbx_thread (data=<value optimized out>) at pbx.c:6586
#15 0x000000000056d90b in dummy_start (data=<value optimized out>) at utils.c:1028
#16 0x00007fad0f2b4851 in start_thread (arg=0x7facc2bd3700) at pthread_create.c:301
#17 0x00007fad1082611d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115
(gdb) fr 1
#1  0x00007facdd52bec2 in t38_core_rx_ifp_packet (s=0x7fab29e2ebe8, buf=0x7fab29cbb44b "\002", len=1, seq_no=0) at t38_core.c:457
457	        s->rx_indicator_handler(s, s->rx_user_data, t30_indicator);
(gdb) p *s
$11 = {tx_packet_handler = 0, tx_packet_user_data = 0x0, rx_indicator_handler = 0, rx_data_handler = 0, rx_missing_handler = 0, 
  rx_user_data = 0x0, data_rate_management_method = 0, data_transport_protocol = 0, fill_bit_removal = 0, mmr_transcoding = 0, 
  jbig_transcoding = 0, max_buffer_size = 0, max_datagram_size = 143, t38_version = 0, allow_for_tep = 0, fastest_image_data_rate = 0, 
  category_control = {0, 0, 0, 0, 0}, check_sequence_numbers = 0, tx_seq_no = 0, rx_expected_seq_no = 1, current_rx_indicator = 0, 
  current_rx_data_type = -1, current_rx_field_type = -1, current_tx_indicator = 0, v34_rate = 0, missing_packets = 0, logging = {
    level = 3082, samples_per_second = 0, elapsed_samples = 0, tag = 0x0, protocol = 0x0, span_message = 0x7facdd79bed0 <spandsp_log>, 
    span_error = 0}}