OpenBTS (Open Base Transceiver Station) is a free softare implementation of the GSP protocol allowing the creation of software-based GSM access points that enable standard GSM mobile phones to make phone calls without using traditional wireless providers' networks. In other words, create your own homebrew cellular network!
According to the OpenBTS Project
, OpenBTS is an open-source Unix application that uses the Universal Software Radio Peripheral (USRP) to present a GSM air interface ("Um") to standard GSM handset and uses Asterisk
software to connect calls leveraging SIP and VoIP.
The goal of the project is to reduce the cost of GSM service provision in rural areas and the developing world. They explain, "In plain language, we are working on a new kind of cellular network that can be installed and operated at about 1/10 the cost of current technologies, but that will still be compatible with most of the handsets that are already in the market. This technology can also be used in private network applications (wireless PBX, rapid deployment, etc.) at much lower cost and complexity than conventional cellular."
During the past few Burning Man festivals, OpenBTS has performed a week-long live field test under special temporary WE9XJN authorization to use certain wireless frequencies.