[mod.telecom] Using U.S. Modems in the U.K.

rex@mhuxh.UUCP.UUCP (09/06/86)

Is it physically possible to use a US modem in the UK, given that
it is capable of operating the CCITT V22 (1200 baud) standard?
Please respond via electronic mail or to netnews.

Rex Godby                                       ..ihnp4!mhuxh!rex       
AT&T Bell Labs, Murray Hill, NJ 07974         Tel. (201) 582-3628

paul@dual.UUCP (Paul Wilcox-Baker) (09/10/86)

> Rex Godby AT&T Bell Labs asks if it is physically possible to use a US
> modem in the UK, given that it is capable of operating the CCITT V22
> (1200 baud) standard?

The answer is basically yes.  Electrically the two systems are similar enough
that I would not expect any difficulties, unless you have a Modem that is
powered by current from the telephone line.  Technically, you will be breaking
the law, as you would by connecting a U.K. telephone to the network here.

Almost all British telephone exchanges use dial pulse only, so your Modem
must be capable of dialling in this fashion.  In the unlikely event that
tone dialling is available, the U.S. tones are the same as the U.K. tones.

If the Modem is the only device attached to the phone line, then you will
just require a cable that connnects the U.S. jack to its British equivalent.
If you have some British phones connected to the line as well as the Modem,
you will get a "ping" from the phone bell for every dial pulse dialled by
the Modem.  There are two solutions to this, one is to replace your British
phone by an American one, the other is to use a more complicated adaptor
that shunts the bell during dialling.

For the simple connection method, connect the Red & white wires from the
British cable to the Red & Green wires from the U.S. jack.

As a slightly commercial aside, I can supply you with either a U.K. jack
and cable or with an adaptor box that does the correct thing with the
bells.  I can also send you a schematic by U.S. Mail.

Paul Wilcox-Baker

Tel [415] 549 3854 Ext 36
Telex ITT 470844

Assuming the British location uses the British equivalent of the modular jack, you will need an adaptor
cable.