Verizon has a plan that's specifically for the deaf and hard of hearing. There plan is nationwide messaging. That is probably the best plan you can get if you do not need to use voice.
For verizon you can get the lg env2, voyager, or blackberry storm, just depends on how much you have to spend. Those are their best phones for texting, email, and online stuff. If you want durable get screen protectors, case, and holster. Check out mybat.com for those accessories.
