After being disturbed too many times by unwanted telephone calls, Arduino forum user "wildview" engineered a solution based around an Ethernet-enabled Arduino board. They've created a system that allows HTTP control of a relay shield connected to the Arduino, and then connected the telephone line through the relay. Thus the line can be cut in and out when required. To be honest it could seem to be an example of over-engineering, however it's a great example of how to remotely control items with an Arduino over a network.
Furthemore, if you're going to recreate this yourself - familiarise yourself with the regulations with respect to the public telephone line. Nevertheless, for more information and discussion - visit the Arduino forum. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
When putting together your next Internet-enabled Arduino project - save time, space and money with the Freetronics EtherTen. Apart from being fully Arduino Uno-compatible, it has onboard Ethernet, microSD socket, full USB interface (so you don't need a costly FTDI cable just to upload a sketch!) and supports optional Power-over-Ethernet.