Lucent Technologies INDeX 20AT User Manual page 4

Page 4 - Introduction
MF & Time Break Recall operation
REN Values
INDeX 20AT Telephone User's Guide
The 20AT uses MF signalling and TB recall signalling only.
Contact your telephone line provider if unsure of the type
of signalling you should be using.
During a call, phones can use a recall signal to indicate to
the exchange that they are about to send more digits.
To ring properly when a call arrives all phones draw a
small current from the telephone line. All telephone
devices have a REN value, a measure of how many
'current units' they need to ring properly.
Most telephone lines can provide ringing current for a total
REN of 4. If the total REN of all the devices on the line
exceeds that value, then some of the devices may not ring
when calls arrive.
If it is necessary to connect more devices to a line than it
can support, equipment exists that can increase the total
REN provided by the line. Contact your line provider for
details.
– The 20AT has a REN of 1. It can share the same
telephone line as other telephone devices so long as
the total REN does not exceed that of the line (usually
4).
INDeX standard telephone sockets provide a REN of 2.
38DHB0002UKDU - Issue 1 February 2000