Brother International 1940CN User Guide - Page 178

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 the 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. APPENDIX A A - 9