2.2. Extension numbers

Extension is a short number associated with a user. They can be also assigned to other PBX objects which will be described later.

A single user can have multiple different extensions.

Using extensions is common when people are calling to your company numbers which are connected to auto-attendands. A caller can then dial directly the extension number of a given user or extension number that he knows is of for example a sales department.

Using extensions is also very often when using hardware desktop phones as it is just way more convenient to dial a short number instead of entering username. In callto.net service the phones use a contact book which synchronized with the server but still in some cases using extensions may be faster.