Hi Sam, I started a previous company (caffei.net) and during this time of selling network software that improves end user privacy, battery life, network performance, and total data used to the folks building all the apps all the people use for 2 years, I grew disgusted with how little regard they have for all of the many prepaid people in the world... for whom a sloppily set up RPC connection for some trash 30 second video ad will cost them $0.40. This is why we had that lemonde.fr teardown on HN several months back: apps stuff themselves with third parties that hog up the network and thus battery life and aren't penalized for it. So the phone company we started became a way to exact the proper practices we know we can deliver, and we know that folks would benefit from. But then we started finding a lot of people in far worse situations with their big phone company providers, paying more than $300 a month for less than 2 gigabytes of data (using less than 50mb a month) etc etc. So our morals pushed us because we couldn't find anyone else helping them! Yes, Consumer Cellular, and yes GreatCall, are supposed to be good, but in practice for about 5% of users, they are really, really bad. And yeah I'm a founder.
We use AT&T, Sprint, and T-Mobile networks. We also peer with a few hundred regional carriers around the world.
What is your business application and how big of a cost component are these SIM cards and how many of them would you need? Have you checked out hologram.io? They have a card built for this IIRC.
Always open to ideas! I am james@communityphone.org