Tmobile does have good "TAP" plan. it's $29.99 a month for unlimit data plans on Blackberry (unlimit Email, Unlimit Internet, Unlimit Data (like AIM), 300 Text) If you don't plan to use text that often then it's worth it. I personally don't use text much tho.. I've spoken w/ Tmobile's Blackberry Department. They told me of plan. It's pretty much similiar to Sidekick except Text. All you have to do is to tell them you are deaf and need just a Data Only plan. They'll work out with you. I am a Tmobile Customer for 4 years and never had plm w/ it. I told them I'm going for BB Curve once it come out. That's where I learned of plan. The Represative himself is excited to own one too LOL.
Maybe YOU should call Tmobile Reprensative and Ask them to transfer you to Blackberry Dept. Then talk to them that you want DATA only plan cuz you're deaf and you currently have Blackberry. See if you can ask them to change it to $29.99 a month w/o voice plan. If you don't like their 300 text, then it'll be $5 or $10 extra for Unlimit Text which bring up to $35 to $40 a month which makes sense... Don't curse or swear at Represative! They'll go offensive.. (happens to couple of my friends who made a stupid move)
Sprint have good plan too. Like what Dennis told you.
Sprint Relay Support Center is where you can get $29.99 for Data only plan on Blackberry, Treo, and HSP. BUT for example, IF you got Blackberry Curve which is coming out soon. ASK Sprint if they will setup $29.99 for deaf. Contact Sprintrelaysupport for info before you jump in for one.
As for iPhone under ATT, just wait few months because there are alot of excitements going on this month. Personally, it'll be around $40 a month for TAP. I'd rather wait until Sprint, Tmobile, and Verizon get iPhone.. I would find out how much they offer.
don't shoot the messager before you ask!
Catty