Check out connected car from ATT. Its an OBDII device that plugs into your car. Its called the ZTE Mobley. I then got a USB adapter so i can use it on ac or dc. $20/month unlimited data.
It may fit your needs, or something like that. It's good enough for me to keep me connected when in remote locations, and I need to be connected. I know oxymoron, but it happens.
I also can take it on the boat...rental cars when travelling etc. It's been great for me, the leash has been cut. Also helps out with the kids when driving back and forth to the lake
