| Pin | Name | Function |
| 1 | FG | Frame Ground |
| 2 | TD | Transmit Data |
| 3 | RD | Receive Data |
| 4 | RTS | Ready to Send |
| 5 | CTS | Clear to Send |
| 6 | DSR | Data Set Ready |
| 7 | SG | Signal Ground |
| 8 | DCD | Data Carrier Detect |
| 9 | | Positive DC Test Voltage |
| 10 | | Negative DC Test Voltage |
| 11 | | Not Assigned |
| 12 | (S)DCD | Secondary Data Carrier Detect |
| 13 | (S)CTS | Secondary Clear to Send |
| 14 | (S)TD | Secondary Transmit Data |
| 15 | TC | Transmitter Clock |
| 16 | (S)RD | Secondary Receive Data |
| 17 | RC | Receiver Clock |
| 18 | LL | Local Loopback |
| 19 | (S)RTS | Secondary Request to Send |
| 20 | DTR | Data Terminal Ready |
| 21 | SQ | Signal Quality Detect |
| 22 | RI | Ring Indicator |
| 23 | DRS | Data Rate Selector |
| 24 | XTC | External Transmitter Clock |
| 25 | TM | Test Mode |