RE: [OT] Irish telephone connections

["Stephen Jones" <ukha@xxxxxxx>]

Thanks Keith

I'm thinking of using RJ45 data sockets throughout and hopefully using
RJ45-RJ11 adaptors for whatever outlets are to be for telephones. And
before you say that RJ11 plugs fit into RJ45 sockets, I know but I'd
prefer to use something a little more substantial.

Cheers

Steve

-----Original Message-----
From: Keith Doxey [mailto:ukha@xxxxxxx]
Sent: 31 December 2003 02:41
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] [OT] Irish telephone connections

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 minimise 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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