Hi,
I have a critical issue.
I’m using fax over Twilio SIP trunk with Asterisk and Spandsp. However, our customers’ faxes are failing more often than they succeed — the success rate is less than 50%. I’m unable to reproduce the issue myself.
I’m using pjsip.conf
, and here is the configuration:
[sipcore]
type=endpoint
transport=transport-udp
disallow=all
allow=ulaw
allow=alaw
allow=g729
context=internal
direct_media=no
100rel=no
outbound_proxy=sip:xxxxxxxxxxxxxxxxxxxxxxx:4060\;lr
fax_detect=yes
Here are some relevant fax logs showing the errors:
[2025-07-11 12:56:14.194] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Training succeeded (-4) in state 7
[2025-07-11 12:56:14.194] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Stop T2 (82400 remaining)
[2025-07-11 12:56:14.194] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Switching from V.17 + V.21 to V.17 (-13.55dBm0)
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Carrier down (-1) in state 7
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Trainability (TCF) test result - 21876 total bits. longest run of zeros was 21600
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_C_NON_ECM_RX to T30_PHASE_B_TX
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 0
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 4
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from state 7 to 8
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: CFR with final frame tag
[2025-07-11 12:56:15.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: ff 13 84
[2025-07-11 12:56:16.775] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 8
[2025-07-11 12:56:16.855] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 8
[2025-07-11 12:56:16.855] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from state 8 to 10
[2025-07-11 12:56:16.855] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_TX to T30_PHASE_C_NON_ECM_RX
[2025-07-11 12:56:16.855] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 0
[2025-07-11 12:56:16.855] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 7
[2025-07-11 12:56:16.855] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 0
[2025-07-11 12:56:16.855] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Start T2
[2025-07-11 12:56:16.874] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Carrier down (-1) in state 10
[2025-07-11 12:56:17.494] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Carrier up (-2) in state 10
[2025-07-11 12:56:17.494] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Carrier up (-2) in state 10
[2025-07-11 12:56:17.654] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Training failed (-5) in state 10
[2025-07-11 12:56:17.694] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Carrier down (-1) in state 10
[2025-07-11 12:56:17.694] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Status changing to 'Carrier lost during fax receive'
[2025-07-11 12:56:17.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Carrier up (-2) in state 10
[2025-07-11 12:56:17.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Carrier down (-1) in state 10
[2025-07-11 12:56:17.714] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Carrier up (-2) in state 10
[2025-07-11 12:56:17.774] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Training failed (-5) in state 10
[2025-07-11 12:56:18.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:19.414] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:19.834] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:24.074] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:25.634] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:26.274] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:28.094] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:28.241] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 10
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 T2 expired in phase T30_PHASE_C_NON_ECM_RX, state 10
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Status changing to 'Timer T2 expired while waiting for fax page'
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Start receiving document
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Flushing queued phase T30_PHASE_B_TX
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from state 10 to 17
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 DIS:
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Store and forward Internet fax (T.37): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Real-time Internet fax (T.38): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= 3G mobile network: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= V.8 capabilities: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Preferred octets: 256 octets
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Ready to transmit a fax document (polling): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..1.= Can receive fax: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..10 11..= Supported data signalling rates: V.27 ter, V.29, and V.17
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .1.. ....= R8x7.7lines/mm and/or 200x200pels/25.4mm: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= 2-D coding: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..00= Recording width: 215mm +- 1%
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 10..= Recording length: Unlimited
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .111 ....= Receiver's minimum scan line time: 0ms at 3.85 l/mm; T7.7 = T3.85
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Compressed/uncompressed mode: Compressed
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Error correction mode (ECM): Non-ECM
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= T.6 coding: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= "Field not valid" supported: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Multiple selective polling: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Polled sub-address: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= T.43 coding: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...0 ....= Plane interleave: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Voice coding with 32kbit/s ADPCM (Rec. G.726): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Reserved for the use of extended voice coding set: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...1= R8x15.4lines/mm: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= 300x300pels/25.4mm: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= R16x15.4lines/mm and/or 400x400pels/25.4mm: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= Inch-based resolution preferred: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...1 ....= Metric-based resolution preferred: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Minimum scan line time for higher resolutions: T15.4 = T7.7
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Selective polling: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Sub-addressing: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Password: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Ready to transmit a data file (polling): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...0 ....= Binary file transfer (BFT): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Document transfer mode (DTM): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Electronic data interchange (EDI): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Basic transfer mode (BTM): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Ready to transfer a character or mixed mode document (polling): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= Character mode: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Mixed mode (Annex E/T.4): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Processable mode 26 (Rec. T.505): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Digital network capability: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Duplex capability: Half only
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= JPEG coding: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...0 ....= Full colour mode: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= 12bits/pel component: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= No subsampling (1:1:1): Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Custom illuminant: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Custom gamut range: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 1...= North American Letter (215.9mm x 279.4mm): Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...1 ....= North American Legal (215.9mm x 355.6mm): Set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Single-progression sequential coding (Rec. T.85) basic: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Single-progression sequential coding (Rec. T.85) optional L0: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 0... ....= Extension indicator: Not set
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: DIS with final frame tag
[2025-07-11 12:56:28.854] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: ff 13 80 00 ee f8 80 80 91 80 80 80 18
[2025-07-11 12:56:29.094] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:29.274] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:29.594] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:31.214] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:31.894] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:32.974] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:33.074] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:33.394] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:34.274] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:35.894] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:35.934] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Abort (-8) in state 17
[2025-07-11 12:56:36.754] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Non-ECM signal status is Carrier down (-1) in state 17
[2025-07-11 12:56:36.754] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Status changing to 'Carrier lost during fax receive'
[2025-07-11 12:56:36.754] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_C_NON_ECM_RX to T30_PHASE_B_TX
[2025-07-11 12:56:36.754] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 0
[2025-07-11 12:56:36.754] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 4
[2025-07-11 12:56:36.754] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Carrier down (-1) in state 17
[2025-07-11 12:56:38.075] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[2025-07-11 12:56:38.155] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[2025-07-11 12:56:38.155] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_TX to T30_PHASE_B_RX
[2025-07-11 12:56:38.155] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 4
[2025-07-11 12:56:38.155] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 0
[2025-07-11 12:56:38.155] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Start T4
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 T4 expired in phase T30_PHASE_B_RX, state 17
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Retry number 1
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_RX to T30_PHASE_B_TX
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 0
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 4
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 DIS:
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Store and forward Internet fax (T.37): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Real-time Internet fax (T.38): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= 3G mobile network: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= V.8 capabilities: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Preferred octets: 256 octets
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Ready to transmit a fax document (polling): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..1.= Can receive fax: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..10 11..= Supported data signalling rates: V.27 ter, V.29, and V.17
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .1.. ....= R8x7.7lines/mm and/or 200x200pels/25.4mm: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= 2-D coding: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..00= Recording width: 215mm +- 1%
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 10..= Recording length: Unlimited
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .111 ....= Receiver's minimum scan line time: 0ms at 3.85 l/mm; T7.7 = T3.85
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Compressed/uncompressed mode: Compressed
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Error correction mode (ECM): Non-ECM
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= T.6 coding: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= "Field not valid" supported: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Multiple selective polling: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Polled sub-address: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= T.43 coding: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...0 ....= Plane interleave: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Voice coding with 32kbit/s ADPCM (Rec. G.726): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Reserved for the use of extended voice coding set: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...1= R8x15.4lines/mm: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= 300x300pels/25.4mm: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= R16x15.4lines/mm and/or 400x400pels/25.4mm: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= Inch-based resolution preferred: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...1 ....= Metric-based resolution preferred: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Minimum scan line time for higher resolutions: T15.4 = T7.7
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Selective polling: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Sub-addressing: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Password: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Ready to transmit a data file (polling): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...0 ....= Binary file transfer (BFT): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Document transfer mode (DTM): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Electronic data interchange (EDI): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Basic transfer mode (BTM): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Ready to transfer a character or mixed mode document (polling): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= Character mode: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Mixed mode (Annex E/T.4): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= Processable mode 26 (Rec. T.505): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Digital network capability: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Duplex capability: Half only
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 0...= JPEG coding: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...0 ....= Full colour mode: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= 12bits/pel component: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ...0= No subsampling (1:1:1): Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... ..0.= Custom illuminant: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... .0..= Custom gamut range: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .... 1...= North American Letter (215.9mm x 279.4mm): Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ...1 ....= North American Legal (215.9mm x 355.6mm): Set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 ..0. ....= Single-progression sequential coding (Rec. T.85) basic: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 .0.. ....= Single-progression sequential coding (Rec. T.85) optional L0: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 0... ....= Extension indicator: Not set
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: DIS with final frame tag
[2025-07-11 12:56:41.614] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: ff 13 80 00 ee f8 80 80 91 80 80 80 18
[2025-07-11 12:56:42.935] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[2025-07-11 12:56:43.015] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[2025-07-11 12:56:43.015] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_TX to T30_PHASE_B_RX
[2025-07-11 12:56:43.015] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 4
[2025-07-11 12:56:43.015] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 0
[2025-07-11 12:56:43.015] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Start T4
[2025-07-11 12:56:43.734] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Carrier up (-2) in state 17
[2025-07-11 12:56:43.954] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Framing OK (-6) in state 17
[2025-07-11 12:56:43.954] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Start T4A
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Stop T4A (16320 remaining)
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Rx: EOP with final frame tag
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Rx: ff 13 2f
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Rx final frame in state 17
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Unexpected EOP frame in state 17
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from state 17 to 3
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: DCN with final frame tag
[2025-07-11 12:56:44.914] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Tx: ff 13 fa
[2025-07-11 12:56:44.954] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 HDLC signal status is Carrier down (-1) in state 3
[2025-07-11 12:56:44.954] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_RX to T30_PHASE_D_TX
[2025-07-11 12:56:44.954] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 0
[2025-07-11 12:56:44.954] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 4
[2025-07-11 12:56:46.035] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_D_TX, state 3
[2025-07-11 12:56:46.115] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_D_TX, state 3
[2025-07-11 12:56:46.115] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Starting final pause before disconnecting
[2025-07-11 12:56:46.124] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_D_TX to T30_PHASE_E
[2025-07-11 12:56:46.124] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 0
[2025-07-11 12:56:46.124] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 1
[2025-07-11 12:56:46.124] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from state 3 to 2
[2025-07-11 12:56:46.983] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from state 2 to 30
[2025-07-11 12:56:46.983] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_E to T30_PHASE_CALL_FINISHED
[2025-07-11 12:56:46.983] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set rx type 9
[2025-07-11 12:56:46.983] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX FAX exchange complete
[2025-07-11 12:56:46.983] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX Set tx type 9
[2025-07-11 12:56:46.983] FAX[1083590][C-000001e8] res_fax.c: FLOW FAX FAX exchange complete
[2025-07-11 12:56:46.983] FAX[1083590][C-000001e8] res_fax.c: FLOW T.30 Call completed
Environment:
- Twilio SIP Trunk
- Asterisk v20
- Spandsp v0.0.6
I tried by enabling and disabling ECM(Error Correction Mode).
Could you please help me to troubleshoot and resolve this issue?