| pin | name | direction | description | color |
| 1 | -- | | -- | |
| 2 | DPR | | Digit Present--A signal given to the ACE indicating that the digit lines contain a digit | |
| 3 | ACR | | Abandon Call and Retry---An indicator signal from the ACE that it could not make a connection. Could be 'busy'. | |
| 4 | CRQ | | Call A signal from the DTE that tells the ACE to go 'off hook'Request--- | |
| 5 | PND | | Present Next Digit---A signal from the ACE to the DTE to indicate that the ACE is ready to receive the next digit. | |
| 6 | -- | | -- | |
| 7 | -- | | -- | |
| 8 | -- | | -- | |
| 9 | -- | | -- | |
| 10 | -- | | -- | |
| 11 | -- | | -- | |
| 12 | -- | | -- | |
| 13 | DSC | | Distant Station Connected--Indicator from ACE to DTE that the call is succesfully made. | |
| 14 | NB1-NB8 | | Digit Signal Circuits--Four lines containing a parallel BCD dial digit (10 digits, plus control digits) | |
| 15 | NB1-NB8 | | Digit Signal Circuits--Four lines containing a parallel BCD dial digit (10 digits, plus control digits) | |
| 16 | NB1-NB8 | | Digit Signal Circuits--Four lines containing a parallel BCD dial digit (10 digits, plus control digits) | |
| 17 | NB1-NB8 | | Digit Signal Circuits--Four lines containing a parallel BCD dial digit (10 digits, plus control digits) | |
| 18 | -- | | -- | |
| 19 | -- | | -- | |
| 20 | -- | | -- | |
| 21 | -- | | -- | |
| 22 | DLO | | Data Line Occupied--An indicator that is used by the ACE to let the DTE know that the line it wants to use is used by another device. | |
