| Values | Hang-up cause description | 
| 00 - 0F | Call placement and termination | 
| 00 01 02 03 04 05 | Normal and proper end of connection Ring detect without successful handshake Call aborted, from +FKS or < CAN>  No Loop Current Ringback detected, no answer (timeout) Ringback detected, answer without CED | 
| 10 - 1F | Transmit Phase A and miscellaneous errors | 
| 10 11 | Unspecified Phase A error No answer (T.30 T1 timeout) | 
| 20 - 3F | Transmit Phase B hang-up codes | 
| 20 21 22 23 24 25 26 27 28 | Unspecified transmit Phase B error Remote cannot receive or send COMREC error in Phase B COMREC error in transmit Phase B RSPREC error DCS send three times without response DIS/DTC received 3 times; DCS not recognised Failure to train at 2400 bit/s or +FMS value RSPREC invalid response received | 
| 40 - 4F | Transmit Phase C hang-up codes | 
| 40 41 42 43 44 45 46 47 | Unspecified transmit Phase C error Unspecified image format error Image conversion error DTE to DCE data underflow Unrecognised transparent data command Image error, line length wrong Image error, page length wrong Image error, wrong compression code | 
| 50 - 6F | Transmit Phase D hang-up code | 
| 50 51 52 53 54 55 56 57 58 | Unspecified transmit Phase D error RSPREC error No response to MPS repeated 3 times Invalid response to MPS No response to EOP repeated 3 times Invalid response to EOP No response to EOM repeated 3 times Invalid response to EOM Unable to continue after PIN or PIP | 
| 70 - 8F | Receive Phase B hang-up codes | 
| 70 71 72 73 74 | Unspecified receive Phase B error RSPREC error COMREC error T.30 T2 timeout, expected page not received T.30 T1 timeout after EOM received | 
| 90 - 9F | Receive Phase C hang-up codes | 
| 90 91 92 93 | Unspecified receive Phase C error Missing EOL after 5 seconds Bad CRC or frame (ECM mode) DCE to DTE buffer overflow | 
| A0 - BF | Receive Phase D hang-up codes | 
| A0 A1 A2 A3 | Unspecified receive Phase D error RSPREC invalid response received COMREC invalid response received Unable to continue after PIN or PIP | 
| C0 - DF | - reserved for future standardisation | 
| E0 - FF | - reserved for manufacturer specific use | 
| 00 - 09 | Call placement and termination | 
| 00 01 02 03 | Normal and proper end of connection Ring detect without successful handshake Call aborted, from +FKS or AN No Loop Current | 
| 10 - 19 | Transmit Phase A and miscellaneous errors | 
| 10 11 | Unspecified Phase A error No answer (T.30 T1 timeout) | 
| 20 - 39 | Transmit Phase B hang-up codes | 
| 20 21 22 23 24 25 26 27 28 | Unspecified transmit Phase B error Remote cannot receive or send COMREC error in transmit Phase B COMREC invalid command received RSPREC error DCS send three times without response DIS/DTC received 3 times; DCS not recognised Failure to train at 2400 bit/s or +FMINSP value RSPREC invalid response received | 
| 40 - 49 | Transmit Phase C hang-up codes | 
| 40 41 | Unspecified transmit Phase C error DTE to DCE data underflow | 
| 50 - 69 | Transmit Phase D hang-up code | 
| 50 51 52 53 54 55 56 57 58 | Unspecified transmit Phase D error RSPREC error No response to MPS repeated 3 times Invalid response to MPS No response to EOP repeated 3 times Invalid response to EOP No response to EOM repeated 3 times Invalid response to EOM Unable to continue after PIN or PIP | 
| 70 - 89 | Receive Phase B hang-up codes | 
| 70 71 72 73 74 | Unspecified receive Phase B error RSPREC error COMREC error T.30 T2 timeout, expected page not received T.30 T1 timeout after EOM received | 
| 90 - 99 | Receive Phase C hang-up codes | 
| 90 91 92 93 94 | Unspecified receive Phase C error Missing EOL after 5 seconds Unused code DCE to DTE buffer overflow Bad CRC or frame (ECM to BFT modes) | 
| 100 - 119 | Receive Phase D hang-up codes | 
| 100 101 102 103 | Unspecified receive Phase D error RSPREC invalid response received COMREC invalid response received Unable to continue after PIN or PIP | 
| 120 - 255 | Reserved codes |