How Do Multi-Line Phones Work?

By Simon Slayford

A multi-line phone works in the same manner as an ordinary phone except it has been designed to have two lines. This means that two phones may work off of the same telephone line and may receive the same calls. This can be used to either allow one person to accept multiple important calls or to allow someone to screen calls before passing them on to an executive.

How It Works

The multi-line phone is built with an extension so that another phone or phones may be attached to it. This kind of extension is normally cordless so that the additional phone may be easily placed in another room. Usually both phones will ring at the same time and the call can be picked up on both phones at once. In other cases, phone settings can be changed so that one phone rings and the other shows a flashing light.

Multi-Line Splitter

A multi-line splitter will split the phone line into two or more lines so that additional phones may be connected. This splitter is connected at the telephone jack and requires nothing more than additional cables. However, the two-line splitter is restricted to being used on two line jacks. These can normally be purchased or ordered from the telephone company.


Generally a multi-line phone may either be used in the upstairs and downstairs portions of a house so that calls may be answered from either location. However, they are much more commonly used in small businesses where one or more employees may need instant phone access. Often, multi or two-line phones are used by executives who wish their calls to be taken, monitored or screened by a secretary. This allows the secretary to take a call without using call forwarding or mobile devices.


With a multi-line telephone, it is possible to monitor and screen calls as well as to take more than one call at once or to allow telephone access in different areas of a building. However, the multi-line telephone cannot be used to make more than one outgoing call at once and faces other restrictions similar to those of a normal phone. Anyone wishing to have a multi-line phone in a home must also contact the telephone company in order to verify the decision to choose a multi-way extension.