and it plugs into the cars OBD port.. It needs power and cant be removed or it will not work..
its 10 bucks for 1 gb and 25 bucks for 5 gb.. no contract plan
Says...
: If you exceed the amount of data included in your plan during your billing period, additional data will automatically be provided in increments of 250MB at $14.99 per 250MB on a 250MB plan or 1GB at $10 per GB on the 3GB and 5GB plans. s. Data allowances, including overages, must be used in billing period provided or will be forfeited.
But also says this... so not sure..
Overage Charges & Data Speeds: No charge for overage. However, after all your high-speed data allotments are used, all data usage is slowed to a max of 128Kbps (2G speed) for the rest of the bill cycle. During that period, you will have basic data use for viewing a web page or checking email. Audio and video streaming, as well as other data usage, including usage of data that is sponsored, will be impacted and may not be fully functional. See att.com/broadbandinfo for more details.