This is what I gleaned from fs_cli:

2014-01-05 18:13:08.904735 [DEBUG] sofia.c:5779 Channel
sofia/internal/1000@hpbx.nest entering state [calling][0]
2014-01-05 18:13:08.904735 [DEBUG] switch_rtp.c:927  [  zrtp utils]:
Send <HELLO> ssrc=1538954628 seq=54771 size=144. Stream 40:CLEAR:START
2014-01-05 18:13:08.924723 [DEBUG] switch_core_session.c:1016 Send
signal sofia/internal/1000@hpbx.nest [BREAK]
2014-01-05 18:13:08.924723 [DEBUG] switch_core_session.c:1016 Send
signal sofia/internal/1000@hpbx.nest [BREAK]
2014-01-05 18:13:08.924723 [DEBUG] switch_core_session.c:1016 Send
signal sofia/internal/1000@hpbx.nest [BREAK]
2014-01-05 18:13:08.924723 [DEBUG] switch_core_session.c:1016 Send
signal sofia/internal/1000@hpbx.nest [BREAK]
2014-01-05 18:13:08.924723 [DEBUG] switch_core_session.c:1016 Send
signal sofia/internal/1000@hpbx.nest [BREAK]
2014-01-05 18:13:08.944752 [DEBUG] sofia.c:5779 Channel
sofia/internal/1000@hpbx.nest entering state [terminating][487]
2014-01-05 18:13:08.944752 [NOTICE] sofia.c:6623 Hangup
sofia/internal/1000@hpbx.nest [CS_EXECUTE] [ORIGINATOR_CANCEL]
2014-01-05 18:13:08.944752 [DEBUG] switch_channel.c:3183 Send signal
sofia/internal/1000@hpbx.nest [KILL]
2014-01-05 18:13:08.944752 [DEBUG] switch_core_session.c:1351 Send
signal sofia/internal/1000@hpbx.nest [BREAK]
2014-01-05 18:13:08.944752 [DEBUG] switch_ivr_bridge.c:633 BRIDGE THREAD
DONE [sofia/internal/1000@hpbx.nest]
2014-01-05 18:13:08.944752 [DEBUG] switch_ivr_bridge.c:658 Send signal
sofia/internal/sip:1002@10.0.0.120:5060 [BREAK]
2014-01-05 18:13:08.964735 [DEBUG] switch_ivr_bridge.c:633 BRIDGE THREAD
DONE [sofia/internal/sip:1002@10.0.0.120:5060]
2014-01-05 18:13:08.964735 [DEBUG] switch_ivr_bridge.c:658 Send signal
sofia/internal/1000@hpbx.nest [BREAK]
2014-01-05 18:13:08.964735 [NOTICE] switch_ivr_bridge.c:721 Hangup
sofia/internal/sip:1002@10.0.0.120:5060 [CS_EXCHANGE_MEDIA]
[NORMAL_CLEARING]
2014-01-05 18:13:08.964735 [DEBUG] switch_channel.c:3183 Send signal
sofia/internal/sip:1002@10.0.0.120:5060 [KILL]
2014-01-05 18:13:08.964735 [DEBUG] switch_core_session.c:1351 Send
signal sofia/internal/sip:1002@10.0.0.120:5060 [BREAK]
2014-01-05 18:13:08.964735 [DEBUG] switch_core_state_machine.c:481
(sofia/internal/sip:1002@10.0.0.120:5060) State EXCHANGE_MEDIA going to
sleep
2014-01-05 18:13:08.964735 [DEBUG] switch_core_state_machine.c:415
(sofia/internal/sip:1002@10.0.0.120:5060) Running State Change CS_HANGUP
2014-01-05 18:13:08.964735 [DEBUG] switch_core_state_machine.c:679
(sofia/internal/sip:1002@10.0.0.120:5060) State HANGUP
2014-01-05 18:13:08.964735 [DEBUG] mod_sofia.c:500
sofia/internal/sip:1002@10.0.0.120:5060 Overriding SIP cause 480 with
487 from the other leg
2014-01-05 18:13:08.964735 [DEBUG] mod_sofia.c:506 Channel
sofia/internal/sip:1002@10.0.0.120:5060 hanging up, cause: NORMAL_CLEARING
2014-01-05 18:13:08.964735 [DEBUG] switch_ivr_bridge.c:1524
sofia/internal/sip:1002@10.0.0.120:5060 skip receive message [UNBRIDGE]
(channel is hungup already)


2014-01-05 18:13:08.964735 [DEBUG] switch_ivr_bridge.c:1527
sofia/internal/1000@hpbx.nest skip receive message [UNBRIDGE] (channel
is hungup already)


2014-01-05 18:13:08.964735 [DEBUG] switch_core_session.c:2810
sofia/internal/1000@hpbx.nest skip receive message
[APPLICATION_EXEC_COMPLETE] (channel is hungup already)


2014-01-05 18:13:08.964735 [DEBUG] switch_core_state_machine.c:478
(sofia/internal/1000@hpbx.nest) State EXECUTE going to sleep
2014-01-05 18:13:08.964735 [DEBUG] switch_core_state_machine.c:415
(sofia/internal/1000@hpbx.nest) Running State Change CS_HANGUP
2014-01-05 18:13:08.964735 [DEBUG] mod_sofia.c:558 Sending BYE to
sofia/internal/sip:1002@10.0.0.120:5060
2014-01-05 18:13:08.964735 [DEBUG] switch_core_state_machine.c:48
sofia/internal/sip:1002@10.0.0.120:5060 Standard HANGUP, cause:
NORMAL_CLEARING


Version 1.2.17 git 7712626 2013-12-27 20:52:28Z 64bit works fine.