There was a GSM-to-VoIP node based on a femtocell but the company making it apparently abandoned the idea before shipping very many, if any at all. I suspect the telcos had a small freakout.

In theory one can be transmitting on licensed spectrum inside the home without permits, but I suppose the telcos never envisioned a "3rd party femtocell" that wasn't connected to their services. So I imagine they were faced with drowning under deluge of telco lawyers.

Still, that was a brilliant idea. I think the product was eventually pivoted to shipboard applications. But, with unlimited voice calls on many plans, a roam-to-voip home base station holds less appeal.

Interestingly enough, there are places without any cell phone coverage where being able to enable a small cell site would provide communications. There are also many disaster scenarios where it would be helpful to have such a capability.

In how many places would this be legal though?

Indigenous communities in unserved rural Mexico set up their own open source based gsm networks and successfully pressured the central government after the fact to give them permission, and their efforts are spreading virally. https://rhizomatica.org/ http://www.wired.com/2015/01/diy-cellular-phone-networks-mex... They have occasional hackathons https://projects.osmocom.org/news/46

It's possible to get permits for temporary operation. People have done this at hacker conferences and at Burning Man for example.

The Burning Man GSM base station writeup was a fun read: http://openbts.sourceforge.net/FieldTest/

I'm the CEO of Fairwaves (http://fairwaves.co). We work with telcos, mostly in developing countries. But there are also customers who run our tech in indegineous communities in Mexico (https://rhizomatica.org/), on mining sites, ships and just in their labs as a test tool.

Providing GSM/LTE service in extremely remote locations in third world countries spurred the initial implementations of open source GSM stacks.

Other business models include intelligence and communications interception.

Few companies from German I think that it using OpenLTE & OpenIMS & Kamailio

http://www.ng-voice.com/ http://www.corenetdynamics.com/

Regards

IOT for industrial applications is where it's at. Currently only a handful of competitors in the field. Give me something fanless that can stand -40 to 80 degrees please.

Google's Project Loon is about the only one I know of...