Hi guys,

Currently I’m testing **T.38 support** with **receiveFAX** and **sendFAX** applications and facing below issue.

I use same fax server to test both receivefax and sendfax and call flow is like below.

**A** (fax server) -> **B** (asterisk gateway) -> **SIP server** -> **A** (fax server)

After trying a week finally I managed to establish T.38 negotiation between receiveFAX and sendFAX function but it still failing. I have enabled debug and found below log.

Now I’m lost and have no idea what to check/fix. You help highly appreciated.

Version: Asterisk 16.2.1

```
May 7 18:29:31] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 82: indicator no-signal
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 T4 expired in phase T30_PHASE_B_RX, state 17
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Retry number 2
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_RX to T30_PHASE_B_TX
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set rx type 0
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set tx type 4
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Sending ident 'unknown'
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: CSI without final frame tag
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: ff 03 40 6e 77 6f 6e 6b 6e 75 20 20 20 20 20 20 20 20 20 20 20 20 20
[May 7 18:29:34] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 83: indicator v21-preamble
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 84: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 84: IFP c0 01 80 00 00 ff
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 85: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 85: IFP c0 01 80 00 00 c0
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 86: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 86: IFP c0 01 80 00 00 02
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 87: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 87: IFP c0 01 80 00 00 76
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 88: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 88: IFP c0 01 80 00 00 ee
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 89: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 89: IFP c0 01 80 00 00 f6
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 90: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 90: IFP c0 01 80 00 00 76
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 91: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 91: IFP c0 01 80 00 00 d6
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 92: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 92: IFP c0 01 80 00 00 76
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 93: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 93: IFP c0 01 80 00 00 ae
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 94: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 94: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 95: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 95: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 96: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 96: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 97: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 97: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 98: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 98: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 99: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 99: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 100: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 100: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 101: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 101: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 102: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 102: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 103: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 103: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 104: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 104: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 105: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 105: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 106: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 106: IFP c0 01 80 00 00 04
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 DIS:
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...0= Store and forward Internet fax (T.37): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .1..= Real-time Internet fax (T.38): Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... 0...= 3G mobile network: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ..0. ....= V.8 capabilities: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .0.. ....= Preferred octets: 256 octets
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...0= Ready to transmit a fax document (polling): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..1.= Can receive fax: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ..10 11..= Supported data signalling rates: V.27 ter, V.29, and V.17
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .1.. ....= R8x7.7lines/mm and/or 200x200pels/25.4mm: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= 2-D coding: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..00= Recording width: 215mm +- 1%
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... 10..= Recording length: Unlimited
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .111 ....= Receiver's minimum scan line time: 0ms at 3.85 l/mm; T7.7 = T3.85
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..0.= Compressed/uncompressed mode: Compressed
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .1..= Error correction mode (ECM): ECM
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .1.. ....= T.6 coding: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...0= "Field not valid" supported: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..0.= Multiple selective polling: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .0..= Polled sub-address: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... 0...= T.43 coding: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ...0 ....= Plane interleave: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ..0. ....= Voice coding with 32kbit/s ADPCM (Rec. G.726): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .0.. ....= Reserved for the use of extended voice coding set: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...1= R8x15.4lines/mm: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..0.= 300x300pels/25.4mm: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .0..= R16x15.4lines/mm and/or 400x400pels/25.4mm: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... 0...= Inch-based resolution preferred: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ...1 ....= Metric-based resolution preferred: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ..0. ....= Minimum scan line time for higher resolutions: T15.4 = T7.7
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .0.. ....= Selective polling: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...0= Sub-addressing: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..0.= Password: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .0..= Ready to transmit a data file (polling): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ...0 ....= Binary file transfer (BFT): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ..0. ....= Document transfer mode (DTM): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .0.. ....= Electronic data interchange (EDI): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...0= Basic transfer mode (BTM): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .0..= Ready to transfer a character or mixed mode document (polling): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... 0...= Character mode: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ..0. ....= Mixed mode (Annex E/T.4): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...0= Processable mode 26 (Rec. T.505): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..0.= Digital network capability: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .0..= Duplex capability: Half only
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... 0...= JPEG coding: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ...0 ....= Full colour mode: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .0.. ....= 12bits/pel component: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 1... ....= Extension indicator: Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ...0= No subsampling (1:1:1): Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... ..0.= Custom illuminant: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... .0..= Custom gamut range: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .... 1...= North American Letter (215.9mm x 279.4mm): Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ...1 ....= North American Legal (215.9mm x 355.6mm): Set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 ..0. ....= Single-progression sequential coding (Rec. T.85) basic: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 .0.. ....= Single-progression sequential coding (Rec. T.85) optional L0: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 0... ....= Extension indicator: Not set
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: DIS with final frame tag
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: ff 13 80 04 ee f8 c4 80 91 80 80 80 18
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 107: (0) data v21/hdlc-fcs-OK + 0 byte(s)
[May 7 18:29:35] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 107: IFP c0 01 20
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 108: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 108: IFP c0 01 80 00 00 ff
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 109: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 109: IFP c0 01 80 00 00 c8
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 110: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 110: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 111: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 111: IFP c0 01 80 00 00 20
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 112: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 112: IFP c0 01 80 00 00 77
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 113: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 113: IFP c0 01 80 00 00 1f
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 114: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 114: IFP c0 01 80 00 00 23
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 115: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 115: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 116: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 116: IFP c0 01 80 00 00 89
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 117: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 117: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 118: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 118: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 119: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 119: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 120: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 120: IFP c0 01 80 00 00 18
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 121: (0) data v21/hdlc-fcs-OK-sig-end + 0 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 121: IFP c0 01 40
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_TX to T30_PHASE_B_RX
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set rx type 4
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set tx type 0
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Start T4
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 122: indicator no-signal
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 T4 expired in phase T30_PHASE_B_RX, state 17
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Too many retries. Giving up.
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Status changing to 'Disconnected after permitted retries'
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_RX to T30_PHASE_D_TX
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set rx type 0
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set tx type 4
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from state 17 to 3
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: DCN with final frame tag
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: ff 13 fa
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 123: indicator v21-preamble
[May 7 18:29:40] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 124: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:40] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 124: IFP c0 01 80 00 00 ff
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 125: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 125: IFP c0 01 80 00 00 c8
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 126: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 126: IFP c0 01 80 00 00 5f
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_D_TX, state 3
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 127: (0) data v21/hdlc-fcs-OK-sig-end + 0 byte(s)
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 127: IFP c0 01 40
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_D_TX, state 3
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Starting final pause before disconnecting
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 117: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 117: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 118: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 118: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 119: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 119: IFP c0 01 80 00 00 01
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 120: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 120: IFP c0 01 80 00 00 18
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 121: (0) data v21/hdlc-fcs-OK-sig-end + 0 byte(s)
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 121: IFP c0 01 40
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_B_TX, state 17
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_TX to T30_PHASE_B_RX
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set rx type 4
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set tx type 0
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Start T4
[May 7 18:29:36] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 122: indicator no-signal
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 T4 expired in phase T30_PHASE_B_RX, state 17
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Too many retries. Giving up.
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Status changing to 'Disconnected after permitted retries'
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_B_RX to T30_PHASE_D_TX
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set rx type 0
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set tx type 4
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from state 17 to 3
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: DCN with final frame tag
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Tx: ff 13 fa
[May 7 18:29:39] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 123: indicator v21-preamble
[May 7 18:29:40] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 124: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:40] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 124: IFP c0 01 80 00 00 ff
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 125: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 125: IFP c0 01 80 00 00 c8
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 126: (0) data v21/hdlc-data + 1 byte(s)
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 126: IFP c0 01 80 00 00 5f
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_D_TX, state 3
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 127: (0) data v21/hdlc-fcs-OK-sig-end + 0 byte(s)
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 127: IFP c0 01 40
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_D_TX, state 3
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Starting final pause before disconnecting
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_D_TX to T30_PHASE_E
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set rx type 0
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set tx type 1
[May 7 18:29:41] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from state 3 to 2
[May 7 18:29:41] DEBUG[27498] pbx_spool.c: Filename: /var/spool/asterisk/outgoing/20.call, Retries: 0, max: 3
[May 7 18:29:41] DEBUG[27498] pbx_spool.c: Outgoing SIP/XXX@YYY: DelayedRetry
[May 7 18:29:41] DEBUG[27498] pbx_spool.c: Delaying retry since we're currently running '/var/spool/asterisk/outgoing/20.call'
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.38 Tx 128: indicator no-signal
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Send complete in phase T30_PHASE_E, state 2
[May 7 18:29:42] DEBUG[3783][C-0000002e] res_fax_spandsp.c: FAX session '36' entering phase E
[May 7 18:29:42] DEBUG[3783][C-0000002e] res_fax_spandsp.c: FAX session '36' completed with result: FAILED (Disconnected after permitted retries)
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from state 2 to 30
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Changing from phase T30_PHASE_E to T30_PHASE_CALL_FINISHED
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set rx type 9
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T Set tx type 9
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.38T FAX exchange complete
[May 7 18:29:42] FAX[3783][C-0000002e] res_fax.c: FLOW T.30 Call completed
[May 7 18:29:42] DEBUG[3783][C-0000002e] res_fax_spandsp.c: FAX session '36' is complete.
[May 7 18:29:42] DEBUG[3783][C-0000002e] res_fax.c: channel 'SIP/fax2email-0000002b' - event loop stopped { timeout: 10000, remaining_time: 10000 }
[May 7 18:29:42] DEBUG[3783][C-0000002e] res_fax.c: Shutting down T.38 on SIP/fax2email-0000002b
[May 7 18:29:42] DEBUG[3783][C-0000002e] chan_sip.c: T38 state changed to 0 on channel SIP/fax2email-0000002b
```