[GreenKeys] Telex Network undergoing a revival (UK)

[Larry]

Jack,

Some notes on telex in Australia compiled in 2000 plus notes re a visit
to
Manchester UK telex exchange.

No dedicated telex exchanges left in Australia.
Haymarket exchange Sydney was switched off in Nov 1999, Paddington
Sydney was switched off in Feb 2000 which was Australia's International
Gateway. The telex exchange is now a Pentium PC.
The network has gone to a system called InTelex, short for Intelligent
Network Telex, using the PSTN as the carrier service.
Telex subs have a telex interface unit that plugs into a telephone line,
which dials a 1-800 number then directs the call to the Intelligent
network at Paddington exchange - there they have a look-up table which
looks up and gets a call line identifier who's object is to verify that
it's is really their telex number, they then call the number and the
look-up table looks up that telex number and directs it to a telephone
number and switches the two calls together. 
     
International trunks come into a telex trunk group converter which is
basically a PC with a 2400 bps interface plugged into the international
trunk bearer via a modem, converts the R101 aggregate signal into the 46
channels and out of that C5 signalling 2meg link which has 30 telephone
trunks on it. Basically it does the same thing that the TRU's do - it
calls the Intelligent network via the look-up table, strips off any
characters we don't want then makes the telephone call. Basically, it is
using the infrastructure that is already there, so no dedicated network
needed. 

At  peak of 37,000 telex subs in Australia, now there are 720 existing
subs [now 400 in 2002] and out of them, approx 240 teleprinters still
being used but as from end of September 2000, Telstra no longer services
telex machines. 
However an ex-Telstra teleprinter tech has started up to offer
teleprinter servicing and will maintain them until the last of them
disappear. Trades using telex are mainly maritime, basically stevedoring
and shipping companies wanting to know where their ships are, and banks
mostly for confirmations of their transfers.

In third-world countries, telex still quite big. In India, there are
70,000 telex lines.  Australia used to have telex telegrams, mainly to
pacific nations, but when telex exchanges were disbanded, those nations
lost their connections so they cancelled all their telex lines. Some of
those countries went Long Line from B.T., others went through HongKong,
possibly Vanuatu went Long Line via France - Fiji just turned their
exchange off. New Zealand turned theirs off too, but Telstra possibly
still retains some NZ customers - they put a MUX between Sydney and
Auckland and installed TRU's in Sydney, and plugged them into their MUX
channels, resulting in very long local lines. 
Telex exchanges changed from Crossbar to AXB, which was very well
thought after as maybe would have still been using it now if a solution
had been found to the infrastructure cost. 

International Telegrams used to run from a huge VAX computer, now it's
run from a Pentium 166 server, with a couple of Pentium monitors and
terminals to type the telegrams in. They run a 75 baud link to London,
actually a 2.4K digital leased private wire telegraph wire link -the
only leased private wire telegraph line in existence but when the
software was written for the differing equipment at either end, a higher
speed capability was not written in. Modem runs at V.22 bis standard,
2400 bps or 1200 bps, depending on line quality and uses a protocol
called XP1 specially written to alleviate any eavesdropping onto lines. 

I visited Manchester UK telex exchange a couple of years ago.
I found they have two switches. The first called Manchester TXMR,
the original switch. This opened about 1984. It's a Canadian Marconi
switch  - 3 processors -  each looks after roughly a third of the
customers - if one fails, the load is split between the other two. By
using software instead of Strowger, you can have out-of-area lines
instead of say all Manchester customers using 66xxxx and Birmingham
33xxxx.
Mr has some London lines, backups every day./ 

2nd newer switch designated Manchester TXMR/2.
Same make, 3 processors - mainly used for new Scottish customers,
Birmingham new customers, new areas. Originally 20 telex engineers in
Manchester, now only 3.

Larry Rice
VK6CP ICQ 532578


-----Original Message-----
From: Jack [mailto:wa2hwj@worldnet.att.net] 
Sent: Friday, 26 April 2002 09:38
To: Larry
Cc: greenkeys@mailman.qth.net
Subject: Re: [GreenKeys] Telex Network undergoing a revival (UK)

Larry,

I assume the UK folks are using TELEX signalling protocols
as a means to utilize an existing backbone network. A neat idea.
Unfortunately, our networks are long gone...most of the internal
TELEX systems in the US were ancient when they were phased
out in the 70's (I think Western Union still had terminal centers
with vacuum tube technology).