How does the hard of hearing person in my family use the tty phones? Is it helpful at all?

The TTY stands for the teletypewriter, and TDD stands for the telecommunication Devices for the Deaf and the Text telephone means a phone that is enabled to send the text over phone lines. All these terms are referring to same device.

Now let’s we know how does a TTY / TDD / Text Telphone work? This device or the phone, when hooked up to the phone or the analog jack, allows for the typing of the messages back and forth between the text telephones. Anybody can call in to the TTY phone (presumably to a hard of hearing or the deaf person) from the relay service, also known as the telecommunications Relay Service or TRS (people love making up acronyms). Under the Title IV of the Americans with the Disabilities Act, this service must be offered free of charge by the every state (just press 7-1-1 to get into touch with a representative from your state relay center). Hope these information comes good for you.