On 06 Dec 2012 01:41:40 +0000 (GMT), Theo Markettos wrote:

Oooh... I just had an evil idea. Drive a relay from a GPIO pin on your
favourite lump of hardware. Use that relay to do loop-disconnect on
the phone line.
snip
All you need is a relay and a power transistor to drive it, plus a few
resistors and capacitors to imitate a phone.

For this just a resistor would do and you don't really need that just
shorting the line will work. Of course this doesn't detect dialtone so if
the line has gone faulty you won't know unless it's calling you.

Basic dialtone detection should be fairly easy, if it doesn't detect it
it could email you. Mind you if there isn't any dialtone the ADSL may
well have gone kaput as well...

--
Cheers
Dave.