I didn’t read every detail about SigFox, it does look interesting. However, it looks very proprietary. If the service ends up being sold in a similar manner as cell service, multiple providers in a given area, it could be successful. It would also require multiple hardware vendors.
I would like to know how they handle 10’s of thousands of devices in a given area at 100 baud. More technical details would be nice to see.
As far as cellular service goes, SparqEE, the rumored makers of the SparqEE CELL modem, is supposedly going to sell service as well. http://www.sparqee.com/portfolio/sparqsim/
(I say “rumored makers of the SparqEE Cell” because I was a backer on the Kickstarter that ended in Sept, 2013. Delivery was supposed to be end of 2013. I will be surprised if I see something by this Sept.)