| Pin | Name | Description |
|---|
| 1 | | |
| 2 | Digit Present (DPR) | A signal given to the ACE indicating that the digit lines contain a digit |
| 3 | Abandon Call and Retry (ACR) | An indicator signal from the ACE that it could not make a connection. Could be 'busy' |
| 4 | Call Request (CRQ) | A signal from the DTE that tells the ACE to go 'off hook' |
| 5 | Present Next Digit (PND) | 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 | Distant Station Connected (DSC) | Indicator from ACE to DTE that the call is succesfully made |
| 14 | Digit Signal Circuits (NB1) | Four lines containing a parallel BCD dial digit (10 digits, plus control digits) |
| 15 | Digit Signal Circuits (NB2) | Four lines containing a parallel BCD dial digit (10 digits, plus control digits) |
| 16 | Digit Signal Circuits (NB3) | Four lines containing a parallel BCD dial digit (10 digits, plus control digits) |
| 17 | Digit Signal Circuits (NB4) | Four lines containing a parallel BCD dial digit (10 digits, plus control digits) |
| 18 | | |
| 19 | | |
| 20 | | |
| 21 | | |
| 22 | Data Line Occupied (DLO) | 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 |
| 23 | | |
| 24 | | |
| 25 | | |
