Just Texting Device Is There A Texting Device(no Talk Time) For Hearing Impaired?

Is there a texting device(no talk time) for hearing impaired? - just texting device

My mother has heard since he was sick as a child. It focuses on text messaging to keep in touch with their children, but not pursued because of cost. I am wondering if anyone knew of a text message only device that can cost less than standard. Or does anyone know if you qualify for any aid, by the fact that they can not get to hear. Thank you!