Ask HN: Cellular for IoT devices?

How do companies like Simplisafe and other similar IoT type devices that have built in 2g/3g, provide the service? Specifically, how are they getting the service, the hardware is not difficult overall. For example, I read this today: http://www.fastcompany.com/3056442/startup-report/why-the-internet-of-things-hasnt-gone-cellular-yet

That article is enlightening although not surprising as it relates to the big cell providers here in the U.S., however, many companies already have cellular enabled products with low to minimal monthly fees. Companies like Simplisafe amongst others, so how are they doing it? Are they doing exactly what Particle did and negotiating individual deals like this to allow off contract, small monthly fees for their product? Or do they become a "virtual" provider themselves and resell the service?