Re: [OT] Irish telephone connections

[Keith Doxey <ukha@xxxxxxx>]

Quoting Stephen Jones <ukha@xxxxxxx>:

> Perhaps a question for our Southern Ireland members -
>
> Can someone please confirm the telephone wiring connections used by
> Eircom? BT use 2 wires (typically Blue and White/Blue) to supply -50V
to
> a master socket which supplies all the secondary sockets with -50V
> between pins 2 & 5 and pin 3 being used for the ringer. But IIRC
> Southern Irish telephones use RJ11 plugs and only the 2 centre pins.
>
> What is the equivalent to BT's master socket?
> Is the line voltage the same as BT, i.e. -50V dc?
> If a RJ45 socket is used for RJ11 plug, is pin 4 (blue) the positive?
> With no ringer signal, do the phones contain the circuitry?
>

Cant comment on Souther Ireland specifically, but most telephone systems
across
the world operate on approximately 50vDC usually negative with repsect to
earth
to mimimise corrosion on external plant.

Some PBX's ( noteably MITEL ) operate on around 24-28V.

For a normal exchange line using just 2 wires, polarity is not normally
important. For UK wiring using 3 wires, polarity is only important between
sockets where all 3 wires are used.

Keith

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