It looks like Google just announced a competitive phone service that is cheaper than T-mobile ($20 per mo without data) and then $10 per month for each 1GB of data at 2x speeds of Tmobile (256 kpbs vs 128 kpbs). 256 kpbs is 3G speed whereas Tmobile gives you 2G. And the data you don't use rolls over.
https://fi.google.com/about/
Domestically it uses the Tmobile & Sprint network. So better than Tmobile solo in the US. Trying to ascertain if there are any downsides. Seems to me that this saves $10 per mo although... it's only available on the Nexus 6 (I currently have the Nexus 5). Might be an upgrade in my future soon.