If you have a smartphone, you have to buy a data plan as well, which could add around $360 a year or more to your bill. And recently, wireless carriers have implemented new pricing, data limits and "throttling" (cutting your data to a trickle if you use too much) that can make figuring out plans downright baffling.
You could be one of those people using a smartphone as you did your old phone — for calling and texting. In that case, you might need only a minimal plan. But discovering mobile movies, streaming music, apps and video chat is like opening a Pandora's box (in fact, Pandora is one of the services you might get hooked on). Your data appetite could quickly grow.
If you like to email, download a few photos and post to Facebook, for example, you can possibly get by on a gigabyte per month, but if you want to stream music and watch the occasional TV show, you may need around 3 gigabytes. And if you're a big video viewer, you're looking at 5 gigabytes or more.
To get a sense of what you may want to do and how much data you'll need, please see our handy chart.