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Open GSM

June 20, 2012

A few of the team (Rachel O’Dwyer, Keith Nolan, Seamus McGettrick & Colman O’Sullivan) have been working on an open GSM installation for the openhere festival we are having at the end of this month. #openhere

We are using the OpenBTS platform.  OpenBTS is an open Base Transceiver Station. The BTS is that part of the GSM network with which the mobile phone interacts.

We like many others are using the OpenBTS software with the USRP hardware.  We have a daughterboard at GSM frequencies. As you will all know you can’t just use mobile phone spectrum because you want to so we had to get special permission from the mobile operators in the vicinity to go ahead and use the spectrum. And of course we can not do high powered transmissions. OpenBTS is typically set up at venues like Burning Man in the Black Rock Desert which means that they have none of these worries.

To get onto our GSM network you have to turn off automatic carrier selection on your phone and actively select the network. Keith altered the OpenBTS software to ensure that when this happens we are all automatically sent a new phone number for the open GSM network. I have put some screen grabs from my phone below. In the first screen grab you can see our network on the list of available networks. It is network 00101 and I have selected that.  In the second screen grab you can see I have been assigned a number. It also shows the welcome back message I got after I turned my phone off and on again.  I was automatically reconnected.

Once connected you can make phones calls to others on the network and send texts. The guys have set up some ‘premium numbers’ which you can ring. Currently you get the privilege of connecting to a recording of dogs barking but they are planning on allowing people to connect to the Father Ted Priest Line! Yes all of this is vital.

So how easy was all this? Not that easy is the answer!

As Colman said after I texted him – that text just cost 1000 Euro (when you factor in the many hours of skilled expertise that had to be put in to getting the system up and running). And so far it is far from stable. The calls drop and the system freezes fairly easily. However everyone is working on getting that sorted.

At the openhere festival we will be discussing whether there is a genuine alternative way of supporting communications that is outside of the traditional mobile operator mindset and traditional operator way of owning and controlling.  For me at the moment we are at a time when things are both opening up and closing down – we can take new control of some things and our control of others is being limited. We need to understand where we are and what we want.

One Comment
  1. At work today some of the guys were at pains to say that the reason why the system is ropey is because it is an open source project – not because there is something so amazing and special behind cellular networks in general!!!

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