Brother FAX-1820C - Manual (Page 27)

INTRODUCTION 1 - 13
Using extension telephones (For U.K. only)
It may be that your premises are already wired with parallel extension
telephones, or you intend to add extension telephones to your line,
in addition to your machine. While the simplest arrangement is
straightforward parallel connection, there are some reasons as to
why this arrangement will cause unsatisfactory service, the most
obvious of which is inadvertent interruption of a facsimile
transmission by someone picking up an extension telephone in order
to make an outgoing call. Additionally, fax receive code may not
operate reliably in such a simple configuration.
This machine may also be set to make a delayed transmission (i.e. a
transmission at a pre-set time). This pre-set job may coincide with
someone picking up an extension handset.
Such problems can easily be eliminated however, if you arrange
modification of your extension wiring circuit, such that extension
devices are connected “downstream” of your machine, in a
master/slave configuration (see fig. 2 on next page). In such a
configuration, this machine can always detect whether a telephone
is in use, thus it will not attempt to seize the line during that time. This
is known as “telephone off-hook detection.”
The inadvisable configuration is shown in figure 1 on next page, and
the recommended master/slave configuration is shown in figure 2.
This new connection configuration can be arranged by contacting
BT, Kingston upon Hull Telecommunications, your PABX maintainer
or a qualified telephone installation company as appropriate. Simply
explained, the extension telephone circuit should be terminated on a
normal modular plug (BT 431A style), which in turn should be
inserted into the modular socket of the white “T”-shaped connector
provided as part of the line cord assembly.