Graham said:
[snip]
Germany uses Annex B (ADSL over ISDN) which is incompatible with Annex A
(ADSL over analogue POTS) as used in the UK and most other places. A
modem/router designed for Germany won't work elsewhere. There are hardware
differences, not just firmware.
Question: do all German subscribers have ISDN, so the only possibility is
ADSL over ISDN?? If not, presumably you have to find out which is provided
at your chosen location.
No, not all German subscribers have ISDN. Deutsche Telekom for a long
time had a strategy though that made it sound as if you can only get
ADSL in a bundle with ISDN.
To translate freely from
http://de.wikipedia.org/wiki/Annex_B :
Annex B is designed for digital telephone lines (ADSL over ISDN). ADSL
is located in a high frequency band, the area below is used for
transmission of ISDN or analogue signals (both work as the frequency
area is broader than in Annex A). The bandwidth needed for ISDN is 140
kHz, the banwidth for analogue telephony only around 20 kHz.
Germany is the only country in the world that exclusively uses Annex B
(ie Annex B also for analogue lines aswell as for ADSL connections
without traditional voice telephony (NGN, pure DSL, bitstream)). In the
rest of Europe mostly Annex A gets used, or in countries with a higher
rate of ISDN lines (such as Switzerland, Scandinavia, Belgium, the
Netherlands or Austria) there is a mix of Annex A (on analogue lines and
for pure ADSL/bitstream) and low-range and low-bandwidth Annex B
(exclusively for ISDN lines).
Other random thoughts that might be relevant:
In Germany you have PPP over Ethernet rather than PPP over ATM as in the UK.
The splitter (microfilter) is always provided by the provider. It goes
into the master socket that requires a TAE plug
(
http://de.wikipedia.org/wiki/TAE) and provides one RJ-45 socket for the
modem and a new TAE socket where either the ISDN equipment or your
analogue telephone. RJ-11 plugs like UK modems use won't work.
The ADSL modems usually support multiple connections, ie if I attach a
hub to my modem and have a friend who visits me, then we both can
connect at the same time using our individual logins and getting one IP
address each. Bandwidth is shared though then.
Regards,
Gunde