Burning Man, the popular desert music festival, is this year featuring a free, solar powered cellular network for the duration of the festival which winds up on Monday. The open source software, OpenBTS (Open Base Transceiver Station) is a low-cost replacement for traditional cell networks. It allows mobile phones to connect to each other if they're all within range of the transceiver, or to connect with any other phones with Internet connection. It utilizes a Universal Software Radio Peripheral (USRP) to create a GSM air interface on any standard GSM mobile phone. The founders of Burning Man, which began this week in Black Rock City, Nevada, have decided to trial the system by allowing the 50,000 or so attendees free access to the network.