Analogue telephone lines

Also known as PSTN lines (Public Switch Telephony Network) these are the basic lines installed in millions of homes and businesses throughout the UK. These can be installed as single lines or multiple lines (eg. 3 lines on the same number).

Multi lines

A variant on the basic analogue line, these are used by businesses as an alternative to a telephone system. For example in an office with 3 users rather than having a telephone system the client can have 3 lines and calls can be transferred around the group.


ISDN lines (Integrated Services Digital Network) come in two variants.


Also known as BRI (Basic Rate Interface) this is the basic digital line which provides 2 voice channels (2 x 64k channels). It offers superior voice quality in comparison with analogue lines.

Most users have ISDN2e for DDI numbering (Direct Dialling Inward), plus it offers CLI (Calling Line Identitity – caller ID) on multiple lines.


Also known as PRI (Primary Rate Interface) this is the mainstay of large business users providing up to 30 voice channels on each line. It offers similar benefits to ISDN2e but on a much larger scale.

Although a knowledge of the terminology relating to business telephone lines may come in useful, it is not necessary to enable you to get the best deal.

With our detailed breakdown you will see where the savings can be made.