Deaf relay is done by transcriptionists. The end user relies on deaf relay in a way where automatic systems are not really an option - possibly in a life and death way if someone is calling their pharmacy or doctor or whatever. It's common for the relay agent to use their human intelligence to navigate a phone menu or get the right party on the line, to rephrase and clarify, since typing is so slow. That's actually a great benchmark for when AI will be ready. Can it replace humans for that task? At present absolutely not. (Trust me I've tried the various speech recognizers. Add a little noise or a mumbly person and it can degrade into uselessness. And the AI isn't going to interrupt someone immediately and then to repeat the last phrase.
Anyway. You need to register for relay service with the provider. Using without would be unauthorized.
Anyway. You need to register for relay service with the provider. Using without would be unauthorized.