I used it for testing purposes, launching telepathy-stream-engine with these lines:

iceman@Rakuen:~ $ export FS_VIDEO_SRC="videotestsrc" //because I don't have a webcam
iceman@Rakuen:~ $ export STREAM_ENGINE_PERSIST=1
iceman@Rakuen:~ $ gdb telepathy-stream-engine

Then, I launched:

iceman@Rakuen:~ $ GABBLE_DEBUG=all /usr/lib/telepathy/telepathy-gabble 

And finally: 

python /usr/share/doc/python-telepathy/examples/call.py /home/iceman/gabble-account <my friend's jabber address>

He picked up the conversation, and after a short while, stream-engine crashed:

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: added transmitter_src 0x81805f0 to pipeline 0x80a28b8
** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec H263-1998 [96]
** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec H263-N800 [97]
** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec H264 [98]
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) prepare_transports: calling MediaStreamHandler::Ready
** (telepathy-stream-engine:6887): DEBUG: Pipeline is not playing, setting to FALSE
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) set_stream_playing: 0
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) set_stream_sending: 0
farsight-rtp-Message: send codec bin not created yet, will set sending later
** (telepathy-stream-engine:6887): DEBUG: Pipeline is not playing, setting to FALSE
OnRequestsignaling called, sending SignalingReady
farsight-transmitter-Message: OnCandidatesReady called with 3 candidates in list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Called farsight_rtp_stream_new_native_candidate
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Native candidates found, adding to list
0x81274e8
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_new_native_candidate: fs_transport->ip = '127.0.0.1'
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Called farsight_rtp_stream_new_native_candidate
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Native candidates found, adding to list
0x81fc950
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_new_native_candidate: fs_transport->ip = '192.168.2.2'
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Called farsight_rtp_stream_new_native_candidate
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Native candidates found, adding to list
0x81f4c18
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_new_native_candidate: fs_transport->ip = '78.22.54.88'
OnRequestsignaling called, sending SignalingReady
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) set_stream_playing: 0
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) set_stream_sending: 0
farsight-rtp-Message: send codec bin not created yet, will set sending later
[New Thread -1258300528 (LWP 6901)]
** (telepathy-stream-engine:6887): DEBUG: Pipeline is playing, setting to TRUE
** (telepathy-stream-engine:6887): DEBUG: _add_pending_preview_windows: called
[Thread -1258300528 (LWP 6901) exited]
[Thread -1241515120 (LWP 6899) exited]
farsight-transmitter-Message: OnCandidatesReady called with 1 candidates in list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Called farsight_rtp_stream_new_native_candidate
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Native candidates found, adding to list
0xb6008130
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_new_native_candidate: fs_transport->ip = '127.0.0.1'
farsight-transmitter-Message: OnCandidatesReady called with 1 candidates in list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Called farsight_rtp_stream_new_native_candidate
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Native candidates found, adding to list
0xb6008798
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_new_native_candidate: fs_transport->ip = '192.168.2.2'
farsight-transmitter-Message: OnCandidatesReady called with 1 candidates in list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Called farsight_rtp_stream_new_native_candidate
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Native candidates found, adding to list
0xb6005f10
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_new_native_candidate: fs_transport->ip = '78.22.54.88'
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) add_remote_candidate: adding remote candidate R1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 192.168.1.107 49363
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) add_remote_candidate: adding remote candidate R2
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 85.27.68.188 49364
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3625): Added remote candidate
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) add_remote_candidate: adding remote candidate R1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 192.168.1.107 49367
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) add_remote_candidate: adding remote candidate R2
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 85.27.68.188 49368
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3625): Added remote candidate
farsight-transmitter-Message: socket state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_new_active_candidate_pair: stream=0x8133800
farsight-rtp-Message: connect state changed to 2
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connected, direction: none
[New Thread -1241515120 (LWP 6903)]
** Message: Connected to ReadPacket
** Message: mutex is 0xb6000bf0
[New Thread -1258300528 (LWP 6904)]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting pipeline to PLAYING returned 1
farsight-transmitter-Message: socket state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_new_active_candidate_pair: stream=0x81338d8
farsight-rtp-Message: connect state changed to 2
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_state_changed: stream 0x81338d8, state: connected, direction: none
[New Thread -1266693232 (LWP 6905)]
** Message: Connected to ReadPacket
** Message: mutex is 0x81a4688
[New Thread -1275085936 (LWP 6906)]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting pipeline to PLAYING returned 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) set_remote_codecs: called
** Message: set_remote_codecs: adding remote codec PCMA [8]
** Message: set_remote_codecs: adding remote codec PCMU [0]
** Message: set_remote_codecs: adding remote codec CN [13]
** Message: set_remote_codecs: adding remote codec telephone-event [96]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: remote_codec PCMA 8000
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: remote_codec PCMU 8000
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: remote_codec CN 8000
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: remote_codec telephone-event 8000
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Remote codec 8: audio PCMA clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Have local codec in the same PT, lets try it first
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Using default codec negotiation function
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Negotiated codec 8: audio PCMA clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Remote codec 0: audio PCMU clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Have local codec in the same PT, lets try it first
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Using default codec negotiation function
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Negotiated codec 0: audio PCMU clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Remote codec 13: audio CN clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Encoding names dont match, local: PCMU, remote: CN
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Encoding names dont match, local: GSM, remote: CN
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Encoding names dont match, local: PCMA, remote: CN
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Could not find a valid intersection... for codec 13: audio CN clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Remote codec 96: audio telephone-event clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Encoding names dont match, local: PCMU, remote: telephone-event
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Encoding names dont match, local: GSM, remote: telephone-event
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Encoding names dont match, local: PCMA, remote: telephone-event
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Could not find a valid intersection... for codec 96: audio telephone-event clock:8000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: caps are: application/x-rtp, encoding-name=(string)PCMU, clock-rate=(int)8000, media=(string)audio, payload=(int)0, channels=(int)1

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: caps are: application/x-rtp, encoding-name=(string)GSM, clock-rate=(int)8000, media=(string)audio, payload=(int)3

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: caps are: application/x-rtp, encoding-name=(string)PCMA, clock-rate=(int)8000, media=(string)audio, payload=(int)8, channels=(int)1

farsight-rtp-Message: farsight_rtp_stream_build_send_pipeline (2662): creating send pipeline with codec 8
(no debugging symbols found)
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: creating send codec bin for id 8, pipeline_factory 0x8144b00
(no debugging symbols found)
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: checking if alawenc is in config list
(no debugging symbols found)
(no debugging symbols found)
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: checking if rtppcmapay is in config list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: linking alawenc0 and rtppmcapay0 with caps audio/x-alaw, channels=(int)1, rate=(int)8000
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: linking src 0x813c000 to codec bin 0x80a2970 with caps NULL
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found audio/telephone-event with PT 96

(no debugging symbols found)
[New Thread -1283478640 (LWP 6907)]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Looking for PCMA or PCMU in the remote codecs
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found PCMA codec with PT 8

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found PCMU codec with PT 0

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found remote_pcma = 1 - remote_pcmu = 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found both the dtmfsrc and rtpdtmfmux installed
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: PCMA found locally? 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: PCMU found locally? 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Looking for PCMA or PCMU in the remote codecs
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found PCMA codec with PT 8

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found PCMU codec with PT 0

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found remote_pcma = 1 - remote_pcmu = 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found both the dtmfsrc and rtpdtmfmux installed
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: PCMA found locally? 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: PCMU found locally? 1
[New Thread -1291871344 (LWP 6908)]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting sending on 0
[New Thread -1300264048 (LWP 6909)]
[New Thread -1308656752 (LWP 6910)]
[New Thread -1317049456 (LWP 6911)]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: We are now PLAYING

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Set_state result was 2

** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec PCMA [8]
** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec PCMU [0]
** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec telephone-event [96]
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) set_stream_playing: 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) set_stream_sending: 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting sending to 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connected, direction: send
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) set_remote_codecs: called
** Message: set_remote_codecs: adding remote codec H263-1998 [96]
** Message: set_remote_codecs: adding remote codec H263-N800 [97]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: remote_codec H263-1998 90000
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: remote_codec H263-N800 90000
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Remote codec 96: video H263-1998 clock:90000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Have local codec in the same PT, lets try it first
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Using default codec negotiation function
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Negotiated codec 96: video H263-1998 clock:90000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Remote codec 97: video H263-N800 clock:90000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Have local codec in the same PT, lets try it first
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Using default codec negotiation function
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Negotiated codec 97: video H263-N800 clock:90000 channels:1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: caps are: application/x-rtp, encoding-name=(string)H263-1998, clock-rate=(int)90000, media=(string)video, payload=(int)96, channels=(int)1

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: caps are: application/x-rtp, encoding-name=(string)H263-1998, clock-rate=(int)90000, media=(string)video, payload=(int)97, channels=(int)1

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: caps are: application/x-rtp, encoding-name=(string)H264, clock-rate=(int)90000, media=(string)video, payload=(int)98

farsight-rtp-Message: farsight_rtp_stream_build_send_pipeline (2662): creating send pipeline with codec 96
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: creating send codec bin for id 96, pipeline_factory 0x816a020
(no debugging symbols found)
[New Thread -1329566832 (LWP 6912)]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: checking if ffenc_h263p is in config list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found config for ffenc_h263p
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: getting prioritize
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: checking if rtph263ppay is in config list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Found config for rtph263ppay
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: getting prioritize
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: linking ffenc_h263p0 and rtph263ppay0 with caps video/x-h263, variant=(string)itu, h263version=(string)h263p, width=(int)[ 16, 4096 ], height=(int)[ 16, 4096 ], framerate=(fraction)[ 0/1, 2147483647/1 ]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting sending on 0
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: We are now PLAYING

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Set_state result was 2

** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec H263-1998 [96]
** (telepathy-stream-engine:6887): DEBUG: fs_codecs_to_tp: adding codec H263-N800 [97]
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) set_stream_playing: 1
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) set_stream_sending: 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting sending to 1
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_state_changed: stream 0x81338d8, state: connected, direction: send
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_new_payload_type (889): received stream with new pt, blocking rtpdemux
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_payload_type_change (899): received stream payload changed to 8
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: rtpdemux_pad_blocked_callback (850): rtpdemux pad blocked, idle_adding create_recv_pipeline
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: call_create_recv_pipeline (822): calling create_recv_pipeline from main thread
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_create_new_pt_recv_pipeline (971): active PT change to 8
farsight-rtp-Message: farsight_rtp_stream_create_new_pt_recv_pipeline (989): setting up new pipeline for id=8
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: creating recv codec bin for id 8, pipeline_factory 0x8144d10
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: checking if alawdec is in config list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: checking if rtppcmadepay is in config list
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: setting queue-delay on depayloader
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: linking rtppcmadepay0 and alawdec0 with caps audio/x-alaw, channels=(int)1, rate=(int)8000
** Message: tp_stream_engine_stream_mute_output: output mute set to off
** Message: tp_stream_engine_stream_mute_input: input mute set to off
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) tp_stream_engine_stream_set_output_volume: setting output volume to 0
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_codec_changed: codec_id=8, stream=0x8133800
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connected, direction: both
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_create_new_pt_recv_pipeline (1071): linking audio sink to codec bin
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_create_new_pt_recv_pipeline: unblocking rtpdemux src pad
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Pad src8 unblocked successfully for farsight_rtp_stream_create_new_pt_recv_pipeline
[New Thread -1339032688 (LWP 6913)]
[Thread -1329566832 (LWP 6912) exited]
[New Thread -1329566832 (LWP 6914)]
[Thread -1329566832 (LWP 6914) exited]
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) add_remote_candidate: adding remote candidate R3
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 192.168.1.107 49371
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3625): Added remote candidate
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) add_remote_candidate: adding remote candidate R4
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 85.27.68.188 49372
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3625): Added remote candidate
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) add_remote_candidate: adding remote candidate R5
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 192.168.1.107 64626
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3625): Added remote candidate
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) add_remote_candidate: adding remote candidate R3
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 192.168.1.107 49375
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3625): Added remote candidate
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) add_remote_candidate: adding remote candidate R4
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3604): adding remote candidate 85.27.68.188 49376
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_add_remote_candidate (3625): Added remote candidate
OnRequestsignaling called, sending SignalingReady
farsight-transmitter-Message: socket state changed to 0
farsight-rtp-Message: connect state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connecting, direction: both
[New Thread -1329566832 (LWP 6920)]
farsight-transmitter-Message: socket state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_new_active_candidate_pair: stream=0x8133800
farsight-rtp-Message: connect state changed to 2
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connected, direction: both
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting pipeline to PLAYING returned 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: We are now PLAYING

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Set_state result was 1

OnRequestsignaling called, sending SignalingReady
farsight-transmitter-Message: socket state changed to 0
farsight-rtp-Message: connect state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connecting, direction: both
[New Thread -1347425392 (LWP 6926)]
farsight-transmitter-Message: socket state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_new_active_candidate_pair: stream=0x8133800
farsight-rtp-Message: connect state changed to 2
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connected, direction: both
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Setting pipeline to PLAYING returned 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: We are now PLAYING

(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Set_state result was 1

OnRequestsignaling called, sending SignalingReady
farsight-transmitter-Message: socket state changed to 0
farsight-rtp-Message: connect state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: connecting, direction: both
[New Thread -1355818096 (LWP 6932)]
OnRequestsignaling called, sending SignalingReady
farsight-transmitter-Message: socket state changed to 0
farsight-rtp-Message: connect state changed to 1
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_state_changed: stream 0x81338d8, state: connecting, direction: send
[New Thread -1364210800 (LWP 6933)]
** (telepathy-stream-engine:6887): DEBUG: connection manager channel closed
** (telepathy-stream-engine:6887): DEBUG: shutdown_channel: disconnecting signals from media_signalling proxy
** (telepathy-stream-engine:6887): DEBUG: shutdown_channel: disconnecting signals from channel_proxy
** (telepathy-stream-engine:6887): DEBUG: channel closed: 0x8072768
** (telepathy-stream-engine:6887): DEBUG: no channels or previews remaining; emitting no-more-channels
** (telepathy-stream-engine:6887): DEBUG: tp_stream_engine_channel_dispose
** (telepathy-stream-engine:6887): DEBUG: tp_stream_engine_session_dispose
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) stop_stream: calling stop on farsight stream 0x8133800
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_stop (3007): stopping media pipeline
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_stop: Setting state to NULL
[Thread -1339032688 (LWP 6913) exited]
[Thread -1308656752 (LWP 6910) exited]
[Thread -1291871344 (LWP 6908) exited]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_stop: DONE Setting state to NULL returned 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Changed pipeline state to NULL succesfully
(telepathy-stream-engine:6887): farsight-transmitter-DEBUG: farsight_lj_transmitter_stop (248): destroying socket client
[Thread -1300264048 (LWP 6909) exited]
[Thread -1221911664 (LWP 6896) exited]
[Thread -1283478640 (LWP 6907) exited]
** (telepathy-stream-engine:6887): DEBUG: stream 1 (audio) cb_fs_state_changed: stream 0x8133800, state: disconnected, direction: none
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) stop_stream: calling stop on farsight stream 0x81338d8
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_stop (3007): stopping media pipeline
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: unlinking source
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: waiting for pad to block
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: pad is not blocked, the next unlink may crash farsight
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: unblocking source
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: done unblocking
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_stop: Setting state to NULL
[Thread -1258300528 (LWP 6904) exited]
[Thread -1266693232 (LWP 6905) exited]
[Thread -1275085936 (LWP 6906) exited]
[Thread -1241515120 (LWP 6903) exited]
[Thread -1317049456 (LWP 6911) exited]
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: farsight_rtp_stream_stop: DONE Setting state to NULL returned 1
(telepathy-stream-engine:6887): farsight-rtp-DEBUG: Changed pipeline state to NULL succesfully
(telepathy-stream-engine:6887): farsight-transmitter-DEBUG: farsight_lj_transmitter_stop (248): destroying socket client
[Thread -1249907824 (LWP 6900) exited]
farsight-Message: Unloading plugin libjingle-transmitter
** (telepathy-stream-engine:6887): DEBUG: stream 2 (video) cb_fs_state_changed: stream 0x81338d8, state: disconnected, direction: none
** (telepathy-stream-engine:6887): DEBUG: tp_stream_engine_session_dispose: disconnecting signals from session handler proxy
farsight-Message: Unloading plugin rtp-session

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1329566832 (LWP 6920)]
0x00000089 in ?? ()

And then, 

(gdb) thread apply all bt

Thread 23 (Thread -1364210800 (LWP 6933)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7adf5e7 in poll () from /lib/tls/i686/cmov/libc.so.6
#2  0xb72b9d0a in ?? () from /lib/tls/i686/cmov/libresolv.so.2
#3  0xaeafa8a4 in ?? ()
#4  0x00000001 in ?? ()
#5  0x00001388 in ?? ()
#6  0x00004000 in ?? ()
#7  0x00000000 in ?? ()

Thread 22 (Thread -1355818096 (LWP 6932)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7af666e in ?? () from /lib/tls/i686/cmov/libc.so.6
#2  0xb7b0039c in ?? () from /lib/tls/i686/cmov/libc.so.6
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 21 (Thread -1347425392 (LWP 6926)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7af666e in ?? () from /lib/tls/i686/cmov/libc.so.6
#2  0xb7b0039c in ?? () from /lib/tls/i686/cmov/libc.so.6
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 20 (Thread -1329566832 (LWP 6920)):
#0  0x00000089 in ?? ()
#1  0xb75bdfeb in cricket::PostThread::OnMessage () from /usr/lib/libjinglebase-0.3.so.0
#2  0xb758f5c7 in cricket::MessageQueue::Dispatch () from /usr/lib/libjinglebase-0.3.so.0
#3  0xb759249c in cricket::Thread::Loop () from /usr/lib/libjinglebase-0.3.so.0
#4  0xb7592622 in cricket::Thread::PreLoop () from /usr/lib/libjinglebase-0.3.so.0
#5  0xb7b6546b in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#6  0xb7ae96de in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 4 (Thread -1230632048 (LWP 6898)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7b69676 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb7f54b71 in ?? () from /usr/lib/libgstreamer-0.10.so.0
#3  0x0818d920 in ?? ()
#4  0x0818ddb8 in ?? ()
#5  0xb6a60384 in ?? ()
#6  0xb6a60358 in ?? ()
#7  0x00000001 in ?? ()
#8  0x0818ceb0 in ?? ()
#9  0xb6a60358 in ?? ()
#10 0xb7c3521c in ?? () from /usr/lib/libglib-2.0.so.0
#11 0x081aa810 in ?? ()
#12 0x080d2948 in ?? ()
#13 0xb6a60358 in ?? ()
#14 0xb7b8abe0 in g_async_queue_unlock () from /usr/lib/libglib-2.0.so.0
#15 0xb7bcd0c8 in ?? () from /usr/lib/libglib-2.0.so.0
#16 0x081aa810 in ?? ()
#17 0x081a4a70 in ?? ()
#18 0xb7b67541 in pthread_mutex_lock () from /lib/tls/i686/cmov/libpthread.so.0
#19 0xb7bcb5af in ?? () from /usr/lib/libglib-2.0.so.0
#20 0x080d2948 in ?? ()
#21 0x0818d188 in ?? ()
#22 0xffffffd8 in ?? ()
#23 0xb6a603d4 in ?? ()
#24 0xb7b29d4e in ?? () from /lib/tls/i686/cmov/libc.so.6
#25 0x081a0cf0 in ?? ()
#26 0xb7b67530 in ?? () from /lib/tls/i686/cmov/libpthread.so.0
#27 0xb7b74ff4 in ?? () from /lib/tls/i686/cmov/libpthread.so.0
#28 0x00000000 in ?? ()

Thread 1 (Thread -1214749008 (LWP 6887)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7ae22a1 in select () from /lib/tls/i686/cmov/libc.so.6
#2  0xb7593a9f in cricket::PhysicalSocketServer::Wait () from /usr/lib/libjinglebase-0.3.so.0
#3  0xb758fab0 in cricket::MessageQueue::Get () from /usr/lib/libjinglebase-0.3.so.0
#4  0xb7592489 in cricket::Thread::Loop () from /usr/lib/libjinglebase-0.3.so.0
#5  0xb77e4b89 in ?? () from /usr/lib/farsight-0.1-2/libjingle-transmitter.so
#6  0xb7ba6551 in ?? () from /usr/lib/libglib-2.0.so.0
#7  0x08159340 in ?? ()
#8  0x081d5640 in ?? ()
#9  0xbff7ad38 in ?? ()
#10 0xb7c3521c in ?? () from /usr/lib/libglib-2.0.so.0
#11 0xb7b68c80 in ?? () from /lib/tls/i686/cmov/libpthread.so.0
#12 0xb7c3521c in ?? () from /usr/lib/libglib-2.0.so.0
#13 0xbff7ad78 in ?? ()
#14 0xb7ba811c in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
Backtrace stopped: frame did not save the PC
#0  0x00000089 in ?? ()

Voilà! I sould also report that, before it crashed, I was hearing my friend just fine, while he couldn't comprehend a single word of what I was telling him, but I guess that's another bug.