Network and Telephone Systems

A telephone network is a telecommunications network used for telephone calls between two or more parties.

There are a number of different types of telephone network:

A landline network where the telephones must be directly wired into a single telephone exchange. This is known as the public switched telephone network or PSTN.
A wireless network where the telephones are mobile and can move around anywhere within the coverage area.
A private network where a closed group of telephones are connected primarily to each other and use a gateway to reach the outside world. This is usually used inside companies and call centres and is called a private branch exchange (PBX).
Integrated Services Digital Network (ISDN)