Hi Jeep. I have the 8320 with service through T-Mobile. The voice plan is self explanatory. The data plans can be a little confusing, but I'll try to answer as best I can.
Unless there is a specific reason, you're better off purchasing the phone through T-Mobile while signing up for a 2-year contract. Retail price w/o contract is around $400-$450. With the 2-year commitment, it's $249 or so.
Most carriers distinguish between just email data transfer and all other data transfer.
If you get your email through the
BlackBerry Internet Service (
BIS), T-Mobile considers this just email access. That means you're given access to T-Mobile's web portal, and you setup the BIS service to pull email from up to 10 different email accounts that have POP3 enabled (most are) -- such as GMail, Yahoo & your local ISP. Emails are then
pushed by BIS to your device.
Emails go to the Blackberry's "Messages" application, so there is no need for a third party email reader, like GMail mobile, and I don't have to go through the web browser to access my email.
The limitation is, in order for it to be considered
only email access, you
have to use BIS and get your email through the Blackberry "Messages" application.
Using the web browser or a 3rd party application like GMail Mobile is considered non-email data transfer.
Choice 1. It's $20/month for the BlackBerry Unlimited Add-on. (I have this). I'm allowed unlimited data transfer for web browsing and email, and the plan includes access to BIS. Of course I can always choose to use the web browser to access your GMail account, or install the GMail mobile application and get to my email through it.
Choice 2. BlackBerry Unlimited E-mail Add-on for $10/month. This plan just gives you access to the BIS push email service. You won't be able to surf on the net. This is probably what the woman at the T-Mobile store meant by needing a data plan.