AT&T is my service provider.
I will not be eligible for an upgrade for quite some time, but the display on my current phone died yesterday.
I need a new phone.

The two major things I'm looking for in a phone are:

1. A full keyboard, preferably the kind that slides out rather than remaining exposed at all times.
2. Free wifi access. Whether that means connecting to my private home network, or connecting to a free network at the local coffee shop. I do not want to incur charges through AT&T by using a private wireless network independent of their services. (Is this even possible..?)

The only phones that offer these two features through AT&T appear to be PDAs and "Smart Phones."
I am not even remotely interested in using GPS location software, email, instant messaging, or any of the billions of applications available through these devices.
I only want to be able to make and receive calls, text, and connect to wifi for internet service outside of AT&T.

If I were to purchase an "Unlocked" cell phone from ebay with full keyboard and wifi hardware, Could I put my current and active sim card in it and still make/receive calls, text, and access free and private wifi networks without purchasing a data plan from AT&T?

Will the "smart phone" even work with my current sim card since it only allocates for texting and calls with no data plan?

See More: Questions about unlocked phones..