I needed some kind of Private Branch Exchange in order to put my collection of old telephones to work. I was given a BT Minimaster 2+10 (2 exchange lines and 10 extension circuits) PABX which fitted the bill initially and which I used for about two years.

The Minimaster is a small electronic PABX which is great for demonstrating old telephones. It is designed for Loop Disconnect (i.e. dial) telephones, and will ring the 1k Ohm bell in old GPO telephones with no problem. This means that it is not necessary to insert a resistor in the bell circuit of the telephones (providing you stick to one telephone per extension.) Compared with more modern systems, however, the Minimaster has limited features and it's big downfall is that it will not work with DTMF (i.e. tone dial) telephones.

In 2000 I replaced the Minimaster with a BT Revelation 4+12 system which is more up to date and has some more interesting options (see below).

In 2003 I installed a BT Inspiration which is BT's replacement for the Revelation. This has a maximum capacity of 8 exchange lines (BT advertised it as maximum 6) and 18 extensions. Revelations and Inspirations will also ring a 1k Ohm bell and they support DTMF telephones. Moreover, they will actually convert LD signalling on the extensions to MF signalling on the exchange lines - so even if the UK telephone companies eventually drop LD signalling (as Telecom New Zealand are in the process of doing) you can still use your old telephones if you have a Revelation or Inspiration!

Programming the Revelation and Inspiration is simple enough, but you need a system phone to do it. The system phone may be disconnected once the system is programmed. The Inspiration systemphone is much nicer than the Revelation systemphone and programming is even simpler.

One difference to note between the Inspiration and Revelation is the method used to put calls on hold from LD phones. On the Revelation you dial "1", but on the Inspiration you have to "flash" the hook switch, which I found takes a little practice.

Visit Krazy Keith's website for information on other small PABX systems.

Following is a comparison of the Minimaster, the Revelation and the Inspiration: