The 9-pin Sub-D female connector SPEECH on the front panel of the instrument can be used for connecting a handset to the signalling unit.
AF connector SPEECH
| Pin No. | Signal | Input (I) / Output (O) / Bidirectional (B) |
Description |
| 1 | GND | B | |
| 2 | LH1HAND SETIN | I | AF signals to signalling unit 1 |
| 3 | LH1HAND SETOUT | O | AF signals from signalling unit 1 |
| 4 | GND | B | |
| 5 | LH2HAND SETIN | I | Signals to signalling unit 2 |
| 6 | LH2HAND SETOUT | O | Signals from signalling unit 2 |
| 7 | GND | B | |
| 8 | +5VKEYB | O | Power supply +5.2 V, max. 100 mA |
| 9 | GND | B |