Photographer and software engineer Dave Hunt has posted an article about his most recent project: a DIY cellphone based on a Raspberry Pi (he calls it a PiPhone). It has a touchscreen dialing interface for making calls, and it's built with off-the-shelf components. The total bill of materials clocks in at about $158: $40 for the rPi, $35 for the 320x240 touchscreen, $15 for the LiPo battery, $48 for the GSM module, and about $20 for miscellaneous other minor parts. Hunt says, '[The GSM/GPRS module] allow us to send standard AT commands to it to make calls, hang up, send texts, data etc. Overall a very clever module. Towards the bottom of the white PCB, you can see the SIM Card, which allows the module to associate with my local GSM network, and it’s using a regular prepaid SIM card, bought in my local phone store for €10. Below the GSM module, you can see the on.off switch and a DC-DC converter, which converts the 3.7volts from the LiPoly battery to 5volts needed by everything else.' He points out that the phone is not terribly practical, but it's a neat project. Hunt has done several others, including turning the Raspberry Pi into a controller for time-lapse photography. He'll be publishing the code he wrote for the PiPhone next week.