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Amateur telex over the internet
- this page is a stub
i-Telex is a hobby telex network that allows
vintage telex machine (teleprinters)
to interconnect via the internet, initiated in 2010 by
Fred Sonnenrein, as the successor to the TelexPhone project.
Unlike its predecessor, which used the PSTN/POTS infrastructure,
it uses TCP/IP and Ethernet. The project is promoted by the i-Telex Group,
and uses fully open source hard- and software.
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i-Telex allows communication between teleprinters in a local environment,
e.g. inside the house, as well as with machines elsewhere in the world.
For a minimum configuration, a backplane is needed with at least three
plug-in cards: (1) the i-Telex ethernet interface, (2) a teleprinter
interface and (3) a power supply unit (PSU).
Depending on the type of teleprinter that must be connected, users have
a choice between an old-style interface with 2-wire, 4-wire, single-current
and double current lines (known as TW39), or an FSK-interface
(known as ED1000).
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A suitable backplane is available in various tastes, and the system can
be powered by your own homemade PSU, or by the readily available
transformer plug-in card.
The prices for the individual plug-in cards are very modest.
As a finishing touch, the complete system
can be housed in a 19" rackmount enclosure, such as
this one from Reichelt Elektronik in Germany.
Membership of the i-Telex network is free. There are no subscription fees.
People who are interested in becoming a member of the i-Telex community,
should contact the
i-Telex Group through their website.
➤ Check out i-Telex website (off-site)
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The diagram below shows the topology of a possible i-Telex setup. At the left is
a telex subscriber node, which typically consist of a vintage teleprinter
(optionally with a tape reader, or TR), a
teleprinter connection device (TCD) and
an i-Telex interface. The latter is connected to the internet, either directly
of via the Local Area Network (LAN) in your house, and one or more routers.
At the top is the i-Telex database server, which holds the IDs and corresponding
IP-addresses of all i-Telex subscribers. Your system (subscriber 1) interrogates
the server to find the IP-address of the desired party (subscriber 2). It then
establishes a peer-to-peer connection directly to the selected party.
This means that the conversation is not hosted or handled by any third party.
Due to his background in railway security, the initial developer of the i-Telex
system, Fred Sonnenrein [1], designed the system in such a way that any
single-point-of-faillure is avoided.
For this reason, there is more than one i–Telex database server. If one is
not available, the i-Telex interface automatically tries the next one,
in the same vein as an internet nameserver.
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- Dial-up via rotary dial
- Dial-up via teleprinter keyboard
- Answering machine
- Group messaging
- Interface to PC
- Reception of e-mail via teleprinter
- Web-interface
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TW39 Single/double-current line, 2-wire or 4-wire ED1000 FSK (virtual double-current)
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- Single-current teleprinters (German TW39 standard)
- Double-current teleprinters
- Teleprinters with FSK interface (German ED1000 standard)
- Ethernet interface
- Analogue telephone interface
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- i-Telex Standard
- i-Telex Light
Analogue modem
- TW-39 Standard
- TW-39 Plus
- ED1000
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- Backplane Basic
- Backplane 4TR
- Backplane 7TR
- Power Supply Unit
- Power Supply Unit Plus
- Transformer Unit
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Although it is possible to build the cards (below) into any suitable
enclosure by means of direct wiring between the boards, it is more
convenient to house it inside an industry standard Eurocard enclosure
such as the one shown here.
Suitable eurocard enclosure are avaiable from
Reichelt in Germany.
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This is the most important part of the installation as it provides
the ethernet interface for connection to the internet. It contains
an upgradable microcontroller that supports the i-Telex protocol
over TCP/IP. For each i-Telex node, you need one i-Telex card.
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This card supports the older TW39 teleprinter protocol, which is
based on current loop signalling. Most (older) vintage teleprinters
are of this type. The card support all known configurations, including 2-wire,
4-wire, single-current and double-current.
Up to two teleprinters can be connected to a single
TW39 card.
Note however, that in most cases you
need a TCD between the teleprinter and the TW39 card.
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This card support the later ED1000 teleprinter protocol, which is based
on two-tone signalling, also known as Frequency Shift Keying (FSK). Some
later vintage teleprinters are of this type.
Up to two teleprinters can
be connected to a single ED1000 card.
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This card provides the power supply to the other cards, plus the
signalling voltages for the TW39 interface.
Note that, in addition to this card, you also need a transformer.
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Device Telex over internet Purpose Connection to i-Telex hobby telex network (via the internet) Name i-Telex Manufacturer i-Telex Group Country Germany Interface Ethernet Protocol TCP Port 134 Format Baudot (ITA-2), ASCII (ITA-5)
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© Crypto Museum. Created: Wednesday 04 September 2024. Last changed: Wednesday, 18 September 2024 - 07:42 CET.
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