A telephone connected to the UW telephone system. Each extension has a unique 5 digit extension number, usually preceded by 6. A multi-line telephone may have several extension numbers.

Are the telephones and terminals connected to a Siemens telephone system. Also known as handsets, phones, telephone instruments, work points and work stations. They can be:- Analogue: including ordinary telephones, Fax machines, modems or DECT cordless Digital: are Siemens system phones including Optiset & Optipoint 500 ranges Integrated Cordless: Siemens Gigaset range for inclusion with Siemens Cordless Systems IP Hard phones: Optipoint 410 & 420 ranges; similar to the Optipoint 500 range but utilising VOIP IP soft phones: Opticlient 130 is a PC hosted VOIP phone See our “Optipoint Handsets” section for further information on Optipoint phones

A telephone, usually connected to a PBX, which does not have direct access to the public network.

an additional telephone set that is connected to the same telephone line

a 'slot' or channel of communication for a telephone or device

A dialing number of 1 to 5 digits assigned to each telephone connected to your System 75.

On a PBX or key system, a telephone or equipment connection.

the physical telephone handset at which an agent takes/makes calls

A unique number that identifies a phone - in practice, each telephone in a phone system.

(1) A telephone number which is local to the switch. (2) Additional equipment on the same line and on the same premises, but at a location other than the main station. (3) Each telephone served by a PBX.

Any telephone other than the main telephone connected to a direct exchange line or to a PBX. Technically PAX telephones are not extensions because they do not extend a public exchange line; instead they should be called stations. Similarly telephones connected to a House Exchange Systems are not extensions because they all have equal status, yet none is the main telephone.

A number that you can dial to reach a user or a service. An extension is a SIP name. Extensions are a PBX concept, not a SIP concept. SIP just knows about URIs. Practically speaking, extensions are useful because you can dial them on a numeric phone keypad. Users don't have an extension property. Rather, an extension can be assigned to a user either as their user ID (typical) or as an alias.

A telephone extension is an internal telephone line attached to a PBX or Centrex system. The PBX operates much as a community switchboard does for a geographic telephone numbering plan and allows multiple lines inside the office to connect without each phone requiring a separate outside line. In these systems, a dialer usually has to dial a number (typically 9) to tell the PBX to connect with a landline (also called DDCO) to dial an external number.