In uk.telecom John Rumm wrote:
Well if you want to get posh, a Draytek Vigor 2830 has triple wan
capability, VPN termination and the ability to fall back to POTS modem
dialup if required. Also various VoIP capabilities with POTS
passthrough. (quite a decent router, and 802.11n wifi box as well)

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. Write some software to generate pulses with appropriate timing.
Take the phone off-hook (close the relay), click the relay to pulse dial
your way to an appropriate number, wait for a bit, put the phone on-hook
again.

All you need is a relay and a power transistor to drive it, plus a few
resistors and capacitors to imitate a phone.

Theo