Glossary definition of Ringer Equivalence Number

Also known as: REN

Ringer Equivalence Number (REN) is the limit set by a Service Provider for the total number of telephones that may be connected simultaneously to a standard wired telephone line.

The reason for setting a limit is because the ringer of each phone will place a loading effect on the line. A normal telephone usually has a REN figure of 1 (the actual number is usually printed on the telephone equipment), and so if the REN limit is set at 4 (as it is for British Telecom in the UK), then four such phones may be connected to the line.

However, not all telephone equipment has a REN of 1, and so it is the responsibility of the customer to ensure that the total of all the REN numbers does not exceed the limit set for the line.