Connecting a German ISDN phone to a UK DSL line

I am looking for advice - I bought a Siemens Gigaset SX675 ISDN phone in Germany and now live in the UK. I have BT Broadband (DSL) at home, but so far have not been able to connect the phone even though I have tried to use a standard UK phone adaptor. Is there an adaptor one can use to connect from the Gigaset base station to the ADSL splitter box supplied by BT ? All assistance gratefully received as I am out of ideas...

YorkshireLad6 where are you?

It won't work. Buy a new phone.

Bloody, 'el, how quick do you want me to reply? It is Sunday, for heavens sake...
As Wheel points out, it won't work. It's nothing to do with broadband or DSL - most UK phone lines are simply analogue ("POTS") lines, so won't work with ISDN equipment, and there is no simple (=cheap) adapter that will help. Had you a UK ISDN phone line (not common, primarily because they are so expensive in UK), then it would work fine...

With one of the Fritz Boxes with an internal ISDN S0-Bus then you should be able to do it - you may have to hack the firmware though to get it to work on Annex A (the UK broadband standard), although for some models there are international or even English firmwares available.

Not a cheap solution. Only the Fritzbox 7050 officially supports Annexe A firmware. This is no longer manufactured, but is still for sale in UK. The AVM implementation of the S0 protocol is sometimes problematic, but it should work with the Siemens device. The cost of the Fritzbox outweighs the value of the phone, but it does have other uses (modem/router/WLAN/VoIP) which may make it worth considering.

7170 also has an internal S0 and available Annex A firmware, albeit German language (Swiss/Austrian version), but that's even more expensive than a 7050.

Apart from which there's a nice easy way to convert any Fritz!Box to Annex A which you can get at ip phone forum (German language!) - on the same forum there's also instructions for hacking the firmware to English language if necessary, so you could get something relatively cheap like the 5050 from ebay and modify it.

Thanks very much for your replies and information about the Fritz box - seems like there is no quick and easy solution here.