(1) A monthly subscription to a cellular or other wireless carrier for the transfer of data over its network. It may be an unlimited-use plan or based on the actual amount of data transferred. See carrier data plans.
Samsung Corby II: Not everyone needs or can afford a smartphone with a full data plan.
Also bear in mind that to make full use of the Apple iPhone's functionality, you need to subscribe to a data plan that will allow you to enjoy high-speed internet and wireless email while on the go.
The most obvious things to look at when choosing your plan are the number of minutes included, the number of text messages included, and what sort of data plan they will be offering you.
Make sure that you have an adequate data plan before proceeding, but you can see how wireless broadband is a quantum leap in robustness above older wireless technologies like GPRS/EDGE.
For example, the iPhone data plan being offered by AT&T cannot be used for tethering purposes.