Detailed Security System & Fire Alarm Definitions
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Phone Systems Definitions

Analog- Term comes from the word "analogous" which means "similar to". This means that the transmitted signal remains unchanged, or not digitized, as it passes through an electronic system. A communication system in which the signal is transmitted and received in its original form. In telecommunications, the voice spoken into the handset is converted into an electrical signal (sine wave). That signal remains unchanged as it passes from telephone to telephone (internal call) or telephone to CO (outside call).

Digital - The term used to describe the conversion of information into a binary code. A communication system in which the signal is encoded into a digital bit stream. In telecommunications, the voice spoken into the handset is converted either in the telephone or the control unit into a series of pulses which represent the audio level and frequency.

Hybrid - A Hybrid key system can use single line telephones (SLT) in addition to an electronic proprietary telephone.

Digital Super Hybrid - A Digital Hybrid key system can use single line telephones (SLT) in addition to an electronic proprietary telephone. In addition it may contain features found only on a digital system.

Add-On Modules - Add on modules expand system capabilities.

Universal Ports - Universal Ports can accept a Standard phone, an analog proprietary phone, or a digital proprietary phone.

HFAB - Hands Free Answer Back. Allows a speakerphone user to talk to an internal caller without lifting the handset. Also used to monitor a room.

SLT - Single Line Telephone. A standard telephone.

Apits - Analog Proprietary Integrated Telephone System. Apits usually refers to an analog 7000 series telephone.

Dpits - Digital Proprietary Integrated Telephone System. Dpits usually refers to a digital 7200 series telephone.

Control Unit - This is the heart of the telephone system. This unit is usually installed in the telephone room or ventilated closet. It contains the Central Processing Unit.

DISA - Direct System Access. This feature allows callers from the outside to access specific system features as if they were an internal extension user.

CO Lines - Central Office Telephone Line.

PBX - Private Branch Exchange. This is a small version of the phones company's larger switching system.

XDP - Extra Device Port. The XDP expands the number of telephones available in the system by allowing a Digital Proprietary Phone (Dpits) and a Single Line Telephone (SLT) to be connected to the same telephone jack but having different extension numbers.

FWD/DND - Forward/Do Not Disturb. Allows users to forward their phones to other extensions on the system. Example: to another extension, to voice mail, or to an outside line. Do Not Disturb is used to block calls from coming into a users extension.

OHCA - Off Hook Call Announce (OHCA) allows a user to inform a busy extension that another call is waiting by talking through the built-in speaker of the called party's proprietary extension.