Dave Plowman (News) wrote:

In article ,
The Natural Philosopher wrote:

Ther are only two wires which connect you to the exchange, and the way
round they are is not important.


It's not 'important' how you connect mains line and neutral either in that
most things will still work. But not good practice.


I am FAIRLY sure that any phone/PABX 'to spec' WILL work. those thet
take power have full wave rectifiers and I am ALMOST sure that teh voice
signal has to be tansformer coupled anway..


Identify those, extend them and put your own master box in.


Stick a DVM which reads over 50 volts DC across the line. With a positive
reading from that, the positive is terminal 5 and the negative terminal 2

No harm in doing things a standard way tho ;-)