Watching the latest news on the Egyptan revolution, hearing that the regime have shut down all the GSM infrastructure, a memory came to my mind: I read something about a smart thing called OpenBTS, a low cost, open source GSM base station. So i did a little research where the project evolved to, and found some really interesting things:
(it46.se) Low cost open GSM base station for developing countries
Published: 24 Aug 2009
What did you do during your summer holidays? I was building my own GSM network!
I have been waiting almost 20 years to make this phone call!. Back in the 90’s when I started my engineering studies and discovered GNU/Linux, dreamed with a system that could do what I have right now on my table :). The first attempt was in 2001 when I was completing my PhD at KTH in Sweden. During those years a group of researchers in the Laboratory started to explore the possibility of replacing as much of the GSM architecture (BSC, MSC) for open source software. Although we had a commercial GSM container with plenty of noisy equipment, the project got stuck trying to find documentation for the GSM internal interfaces.
In December 2008, I attended a conference about Mobile Service in Developing Regions. I was very surprised not to see anyone addressing the need of opening the GSM infrastructure (hardware and software). Christmas period was a good time for new projects so I decided to get in touch with the openbts project and try to build their base station. Assembling all the necessary hardware took a bit of time! David Burguess from openbts has been really helpful with hardware purchases!.
Yes! It does work, and that first phone call felt like a different one :D. The base station uses a piece of hardware known as USRP. The USRP is a radio communication system where components that have typically been implemented in hardware are now implemented using software in a PC.
We are looking for sponsors for a deployment in a developing region! Interested? Drop us a line!
Posted by: Alberto Escudero-Pascual
(taranfx.com) Open Source GSM Base Station [OpenBTS]
Closed Technologies have had the enough, the future is bound to be open. I can’t think of a stream where Open source has not contributed. In few of the relatively newer streams, like telecom, Open source is still catching up.
I had been into telecom for a long time now, and had often heard a complaint from Telecom startups and sometimes even giants about the cost to go to the market in rural/developing areas. A simple BTS (a.k.a Mobile antenna) could cost anywhere from thousands of dollars to millions (depending upon the capability 2.5G, 3G, 3.5G, 4G).
OpenBTS is one project that can change the game by bringing down costs.
Basically OpenBTS is a Base Transceiver System [BTS] with open source implementation of cellular interface for GSM using software that runs on open source hardware called USRP [Universal Software Radio Peripheral]. Using this, a cellphone interface can be achieved, just like any other GSM phone does.
On the network back-end, it is an Asterisk server. The system doesn’t have much to do with signalling susbsytems, at layer 3, GSM call control is very much like ISDN. What they have implemented is GSM air interface in layer 1, GSM air interface LAPDm in layer 2, and then in layer 3 is very much like ISDN SIP gateway.
The two things they support, right now, are speech: Q.931-type call control, and text messaging, SMS.
All that’s exposed to the BTS is the air interface, because of this all the complexity in the network is pretty much abstract. As the lead developer claims, “It’s not that complicated”. he says “Once you understand the specification, it’s not that complicated. We have had three people working on this project for about two years, well, for about eighteen months of actual programming. We started coding this stuff in August of 2007.” and finished in December 2009
The short-term goal of the project is to find a sponsor for a pilot deployment in a rural area, in the developing world. They are trying to get one in Africa, in India, and in Central America. Because it can be deployed and operated at much lower costs, you have the potential to push the cost of service down to $1 a month range.
The plan looks good, all we have to see is how fast the adoption is. The project is willing to learn from your experiences on the platform. Yes, at this time it’s pretty much 2G [with no packet or even circuit switched data] but it ain’t bad for a new idea, new open project.
On the other note, from what we have seen in the past – GSM is very much hackable and having a new Open source project that can replace GSM with a more secured System could make more sense.
(wikipedia) OpenBTS#Field tests
Live tests of OpenBTS have been conducted in the United States in Nevada and northern California. The necessary temporary radio licenses were applied for through Kestrel Signal Processing (KSP)—the original authors’ consulting organisation firm—and granted for a short period of time.
During the Burning Man festival in August 2008, a week-long live field test was run under special temporary authorization (STA) license WD9XKN. Although this test had not been intended to be open to Burning Man attendees in general, a number of individuals in the vicinity succeeded in making real out-going calls after a mis-configured Asterisk PBX installation allowed test calls prefixed with an international code through.
The Burning man test successfully connected about 120 phone calls to 95 different numbers in area codes over North America.
A second, larger test was run using a 3-sector system at the 2009 Burning Man festival under the STA license WD9XSP, and a 2-sector 3-carrier system was run in 2010.
During 2010, an OpenBTS system was permanently installed on the island of Niue and became the first installation to be connected and tested with by telecommunication company. Niue is a very small (in terms of population) country with a population of about 1,700, too small to attract mobile telecommunications providers. The cost structure of OpenBTS suited Niue, which urgently required a mobile phone service but did not have the volume of potential customers to justify buying and supporting a conventional GSM basestation system.
August 2009, an OpenBTS network was built for the usage of the participants of this congress. The Staff of HAR2009 obtained a license from the Dutch regulatory authority. A few basestations were deployed and used by visitors and participants to call between eachother on the large terrain. 
OpenBTS on Sourceforge, developers official hompage: http://openbts.sourceforge.net/
OpenBSC is a project aiming to create a Free Software, (A)GPL-licensed software implementations for the GSM/3GPP protocol stacks and elements.
Phones at Burning Man: Can you hear me now?