Actually if you only have a DATA plan and no phone plan....like myself, then you have to have the option #1.
If you have a phone plan, then you can add a DATA plan (#2).
You have to have a DATA plan on a smartphone, but you don't need a PHONE plan.....go figure
Since I have a seperate phone on my corporate account, I don't need a voice plan.. I like to use my smartphone for GPS and email while being able to talk on my other line.