I'm not positive but I don't think you can call a TDD number unless you are using a TDD yourself. Captioned phones work but are typically used to receive printed information rather than send it. But deaf people do communicate with other deaf people on text telephones, so they should work for you.

You may find something on diglo.com They have a catalog of assistive technology. I understand you can hear but not speak.

Did you have cancer surgery that left you without speech? If so have you asked the medical professionals what they recommend?