Your premises may already be wired with parallel extension telephones (those connected to sockets in other rooms in the building), or perhaps you intend to add extension telephones to your line. While the simplest arrangement is a parallel connection, there are some reasons why this arrangement may cause problems.
The most common problem, is someone picking up an extension telephone while the machine is trying to send a fax.
Such problems can easily be eliminated, 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 figure 2). In such a configuration, this machine can always detect whether a telephone is in use, so 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, 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 PBX 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.
| 1. | Extension socket |
| 2. | Master socket |
| 3. | Incoming line |
| 1. | Extension socket |
| 2. | Master socket |
| 3. | Incoming line |
