Jeff Murchison has described how to control a range of older, inexpensive Motorola GSM mobile phone handsets with an Arduino - and the goal of his exercise is to send SMS text messages from the phone. To do so with the handsets noted in his tutorial is very simple due to the serial interface on the phone and the plug used. Furthermore, considering you don't have to muck about with a GSM shield, power supply, antenna and so on - this is much easier. And a quick look at Internet auction sites found Motorola C261 handsets for around $50.
A simple and inexpensive solution to sending SMS from an Arduino. To find out how, click here for Jeff's pages. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're looking for other ways to send messages from an Arduino, consider using the Internet with our 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.