| Tail circuit (dce-dce) | ||
| 2 | <-> | 3 |
| 3 | <-> | 2 |
| 4 | <-> | 8 |
| 8 | <-> | 4 |
| 6 | <-> | 20 |
| 20 | <-> | 6 |
| 7 | <-> | 7 |
| Null modem (dte-dte) | ||
| 2 | <-> | 3 |
| 3 | <-> | 2 |
| 7 | <-> | 7 |
| 4&5 (internal only) |
4&5 (internal only) |
|
| 6&8&20 (internal only) |
6&8&20 (internal only) |
|
| Tail circuit (dce-dce) | ||
| 2 | <-> | 3 |
| 3 | <-> | 2 |
| 4 | <-> | 8 |
| 8 | <-> | 4 |
| 6 | <-> | 20 |
| 20 | <-> | 6 |
| 7 | <-> | 7 |
| Null modem (dte-dte) | ||
| 2 | <-> | 3 |
| 3 | <-> | 2 |
| 7 | <-> | 7 |
| 4&5 (internal only) |
4&5 (internal only) |
|
| 6&8&20 (internal only) |
6&8&20 (internal only) |
|