Basic Telephony

Chapter 3: Types Of Telephone


This chapter explains how the different types of telephones work.

1. Analogue Telephones

As we saw in the previous chapters, the telephone that Bell and Edison developed has remained remarkably unchanged to this day. But with the introduction of digital exchanges the opportunity was there to develop digital telephones that offered more features to the user. This development has been rapid in the private (PBX) markets but the public telephone system - the phone in your home - has remained almost unaltered!

Push Button Telephone



Learn how analogue telephones connect and dial.

2. Digital Telephones

Most manufactures of private exchanges offer a range of digital telephones. Mitel have the name 'Superset' for theirs. These telephones connect using two wires as normal but the signal is in the form of a 'data message' between the phone and the circuit card the phone connects to. Dial tone and ringing are generated within the phone, rather than in the PBX. Using digital signalling means a lot more information can be sent between the phone and the PBX such as Calling Line Identity  - the callers number; the name of the person calling; ability to light message waiting indications and many more. Digital telephones cost more than analogue ones, but offer many more features.

4150.jpg (84756 bytes)

Mitel Superset 4150 Digital Telephone - click to enlarge


Learn more about digital telephones

3. IP Telephones

The latest development in telephones is the IP telephone. This uses Internet Protocol to send and receive information from the PBX. The analogue and digital telephone need a dedicated physical connection directly to the circuit card in the PBX. IP telephones are connected anywhere on the computer network of the office and communicate with the IP PBX using data 'packets' just like a computer. IP telephones are much easier to install as they don't need a dedicated wired infrastructure; and like digital telephones offer the user a huge range of advanced features.

pdatel.jpg (117328 bytes)

Mitel IP Superset with PDA - click to enlarge


Learn more about IP telephones

Chapter 4: Telephone wiring