Multi-line access can only be activated by terminals which have been specially configured using AMO KCSU. Terminals configured for this purpose will be referred to as Keysets in this document.

Multi-line access allows seizure of a primary line (initial line) and up to 28 secondary lines from a Keyset for incoming and outgoing calls. Every line corresponds to a station number. One line can be assigned to as many as 40 different terminals. For every line there is a line key with LED on the terminal. The LED signals the line state. Free: LED is off, seized: LED is on, call state: LED flashes rapidly, call on hold: LED flashes slowly.