[CaptainMcCrank]

It is interesting, but I think it is a dead end. The concept is possible because GSM doesn't require mutual authentication. Consequently, devices can "relatively" easily attach to a tower, if a bunch of circumstances are true.

Umts requires mutual authentication, so any devices that will connect must be preconfigured to do so. This means that attaching to your own tower becomes a lot less simple: each device must be configured to work with your own cloud.

I think it is a dead end because gsm will be phased out eventually. This is only "easy" today because many phones are dual stacked gsm/umts.

OpenBTS really started some interesting work in this space, but I think openBSC is the more advanced (and less approachable) soloution. OpenBSC recently reported some small ability to support a little bit of GPRS. Without GPRS support, there is no ability to do data on your phoney tower. Unfortunately, the hardware on openBSC is less accessible.