US DSL Modem in Europe

[Ivor Jones]

Dennis Ferguson wrote:
[snip]

I've also never seen an ADSL modem
with anything other than an RJ-11 socket for the
telephone interface, no matter what the national
telephone connector looked like.
Are German modems really different, or do you have to
use a magic cable with an RJ-11 on one end and an RJ-45
on the other?

No, I use normal patch cables for the connection between
modem and splitter. My model has three different sockets,
all of which are RJ-45. A picture can be seen here:
http://arktur.schul-netz.de/wiki/index.php/Bild:Dsl_modem.jpg

Regards,
Gunde

I think this is common on German equipment. My AVM Fritz!Box Fon has
RJ45's for both the ADSL connection to the filter and for the fixed line
and Ethernet ports. The fixed line port uses pins 1 & 8 only, with the
supplied lead having a normal BT 431A plug on the other end, which plugs
into the phone side of the filter.

The ADSL cable supplied has RJ45 plugs on both ends and there is an
adaptor supplied with an RJ45 socket and an RJ11 plug that connects to the
ADSL side of the filter on the phone socket. I'm not sure which pins the
ADSL cable uses as I can't see without unplugging it and it's in an
awkward location..! The two VoIP phone ports are standard RJ11 though.

Ivor

 

[Dennis Ferguson]

Thanks for that. You learn something new every day.

I think this is common on German equipment. My AVM Fritz!Box Fon has
RJ45's for both the ADSL connection to the filter and for the fixed line
and Ethernet ports. The fixed line port uses pins 1 & 8 only, with the
supplied lead having a normal BT 431A plug on the other end, which plugs
into the phone side of the filter.

That is truly interesting. Pins 1 and 8 aren't paired in a 100baseT
patch cable (1 is paired with 2, 7 with 8). If German ADSL is also
wired like that it would both explain why an RJ-11 won't work, and in
fact would suggest it would be better not to use a standard 100baseT
patch cable for an ADSL connection in Germany.

And the reason I find it quite plausible is that I'm pretty sure
the 8 pin connector wiring scheme with pins 1 and 8 paired was
the preferred US Bell System arrangement when the 8-pin connectors
were introduced for phone use. Google produces this

http://www.connectworld.net/global/usoc.htm

which shows it as RJ31X, or RJ61 with tip&ring reversed (if you look
at the RJ25 6-pin connector, which fits in the 8-pin socket, you can
see why it makes more sense than RJ45 Ethernet wiring). Pins 1 and 8
were thought to be too far apart for a really high frequency signal pair,
however, so the TIA or someone redid the pairing for non-telephony use,
after which RJ11/RJ14 telephony connectors lost their two outer pins,
shrinking from 6 pins to 4, because the outer pins were no longer paired
with the 8 pin connector wiring that was originally for non-telephony use
but which was increasingly used for everything.

It certainly fits all my stereotypes. The German phone company picks
a standard that makes the best sense for telephony and sticks with it.
The US, which has as many "standards" as it has opinions, leaks a random
selection of them out into the wider world for various purposes (oddly
wired RJ-45s, 4-pin RJ-11s). The German stuff now looks weird.

Dennis Ferguson

 

[Gundemarie Scholz]

Thanks for that. You learn something new every day.


That is truly interesting. Pins 1 and 8 aren't paired in a 100baseT
patch cable (1 is paired with 2, 7 with 8). If German ADSL is also
wired like that it would both explain why an RJ-11 won't work, and in
fact would suggest it would be better not to use a standard 100baseT
patch cable for an ADSL connection in Germany.

Ok, ADSL in Germany only uses two wires, but apparently it depends on
the provider which pins are used. Chatting with a friend I got to know
that Netcologne seems to have used RJ-11, but with the outer pair in
use. And Alice uses RJ-45 in the splitter and RJ-14 in the modem, pins 4
and 5 used.

Sorry for committing yet another German language link, but I liked it
more than the English wikipedia version, and it has pictures and tables
that should be understandable without knowing German.
http://de.wikipedia.org/wiki/RJ-XX

In any case the cable should be twisted pair, not flat. Checking the
cables in the drawer next to me it seems flat cables are the standard in
the UK?

[...]

It certainly fits all my stereotypes. The German phone company picks
a standard that makes the best sense for telephony and sticks with it.
The US, which has as many "standards" as it has opinions, leaks a
random selection of them out into the wider world for various
purposes (oddly wired RJ-45s, 4-pin RJ-11s). The German stuff now
looks weird.

Seems though I was wrong, and local internet access providers have their
own hardware solutions as stated above.

Good night!
Gunde