AT&T is offering text-only service to the deaf. I'm in the process of jumping through their hoops to get such a service, because the cheaper services (such as Virgin Mobile) don't function well in remote areas of Oregon, Idaho, and Montana where I work.
First you have to go to an AT&T store and fight with them, because few know about the new service. Once they have checked and re-checked with their home office and grudgingly say they have the service, then you buy a phone. The cheapest one that will work for me is $125. Then you sign up for AT&T service for at least $60. Then you can apply via a form (and they may ask for an audiologist's certification that you "deaf enough.") Then you can get the reduced text-only service for about $30 a month.
The whole process is audist-contrived and designed so you will give up and not bother them.
My company is fighting this through with me, so I'll let you know.