16
C H A P T E R T W O
Ringer Equivalence Number (REN)
This equipment has a REN value of 1. A BT line has a “bell ringing”
capacity, or REN, of 4. This means that adding downstream-connected
extension telephones and/or extension bells to a total REN of greater
than 4 may cause a reduction in the bell volume. In extreme cases, it may
cause the auto-answer facility of the machine to fail.
Therefore, up to three additional extension telephones (each assuming a
REN of 1), may be connected downstream of your machine. For an
explanation of “downstream connection, read “Using extension
telephones” which follows.
Unless otherwise marked, a telephone provided by BT may be assumed
to have a REN value of 1.