Yeah, kind of odd is right. But, in their defense (and believe me, they need a lot of it), they used to have a coverage map, and it was the same exact image as the coverage map of T-Mobile. Datajack never admitted they used T-Mobile, but when you consider that T-Mobile and Datajack had the same exact coverage map, it's easy enough to point a finger.
Now, they've moved to MiFi and CDMA, which can only mean Sprint or Verizon. Probably Sprint, but until they get an actual coverage map up, there's no way to know for sure.
The reason they just cancel you for going over the 5GB limit is that once you go over, they still have to pay Sprint (or Verizon) the same per-MB charges that a Sprint of Verizon customer would, except that Datajack has no way to force you to pay those charges. And since it's not their network and they have no control over it, despite what they say, they really have no way to "limit throughput speeds, or control the amount of data transferred." Their only option is to "suspend, modify or terminate service, without notice," Even temporarily suspending or modifying the service is something that they would have to keep a watch on and keep track of, having to expend more time and effort than it's worth. So, what they want are people who surf a little, watch a YouTube video now and then, do e-mail, and then shut it down, never coming anywhere near the 5 GB cap. Those who go over are likely to do it again, so they just get rid of them since they're more trouble then they're worth. In reality, it's only about 5% of customers who go over the 5GB cap. It's the same with broadband cable, where about 5% use about 90% of the bandwidth (although with streaming video, especially services like Netflix, that's changing somewhat. However, Comcast managed to recently get a court ruling allowing them to monitor and limit content, such as content like NetFlix and Torrents that could compete with their core cable TV business, rather than abide by "net neutrality"). Those cable providers would just as soon see those customers go elsewhere.
My recommendation is, if you want Internet service, or cell phone service, deal directly who is providing the service, rather than some 3rd party retailer who is piggy backing off the service. A 3rd party service just introduces one more layer of customer service, and at least doubles the number of possibilities that people can pass the buck to for blame.
