You have a couple of important things to consider. First, do you want a smartphone, that is a phone that operates like a computer with applications, the ability to fully access the internet, and the ability to send and receive email. If those things are important to you, then I would recommend the iphone or an Android phone. On ATT you used to have the unlimited data plan, but sadly that’s no longer an option.

I have both an iphone and an Android. They both feature the touchscreen rather than a keyboard, which I have come to prefer.

The iphone 4 is an outstanding device. Sleek and beautifully crafted both the design and interface make using it a pleasure.

Android phones for ATT that have received positive reviews are:
The HTC Aria
Samsung Captivate
Motorola Flipside
Motorola Bravo

Android and iphone will have multiple options for texting applications and keyboards. If you don’t like one, download another until you get the exact look and feel that you want. Personally I love the ability to customize those details so you’re not stuck with just one option.

If all you need is to text, you might just want to get any one of the free models with the keyboard. In that case you will need to pick them up, feel the keyboard, try to type something and see what feels best in your hands. There are currently more than twenty designs with keyboards available and to me, one is as good as the next when texting is your priority. It all comes down to your hands on the keys. Here are some tips from a website linked below that may be helpful.

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Cell phones are known for their tiny keypads and close set buttons. Because some are designed more for placing voice calls the keypad isn't set up for fast and easy text messaging. Not only does it slow you down, but it can be a pain on your hands.

Here are a few tips of things to look for when you are trying to find the best text messaging cell phones:

A full QWERTY keypad. A QWERTY keypad is set up like the keyboard of your computer or a typewriter versus like the typical phone keypad. This makes for much faster texting; especially if you are accustomed to typing.

Menus are also important to consider when searching for the best texting cell phone. You want one that provides easy scrolling through messages.

The best texting cell phone should have a spacious keypad. Not only is a QWERTY keypad important but one that is large enough, with keys that aren't too small or slippery. The best way to determine if the keyboard is sufficient is to try it out in the store. Then go back on line to buy for the best deal.

A screen you can read is also critical. Again, this is personal preference as to how large and how bright you need the screen but check it in a variety of lighting conditions; indoors/outdoors if possible to see if you will be satisfied. Some screens tilt and some allow you to adjust the brightness and font.

The best text messaging phone may also have predictive text. Predictive text can help cut down the number of keystrokes to compose your message.
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