Multiline allows more than one physical line to share the same NUA.
All the lines must be on the same PSE.
This has two uses:
- Loadsharing: eg if 2 X25 lines have same NUA they expect 50% down each link. This will only happen if both lines are on the same switch, not just the same exchange.
- Increased reliability in case of line failure: If a line fails all calls will be sent to the other lines.