Pedro, You are not being rude. You are open to learning! Asking questions is a good way to learn. The original 'relay system' is somewhat antiquated due to all the new apps available on smartphones. Captioned landline phones have been extremely helpful for many people. Now, that technology is also available on cell phones. Some of the smartphone apps do use a middle source to relay messages.

Years ago we were using 'text telephones' or TDDs, which stood for Telephone Device for the Deaf. They could 'talk' to one another as long as the people on both ends of the call were using them. It was all done by typing. The Relay system was used when a middle person was needed to connect the conversations. A relay operator was listening and typing to the person who needed to read the message, and was also relaying it to the other person orally. Keep in mind that some deaf people are oral. Both means of communication were used...oral and written, so the 'relay' point depended on what was needed in each situation.

The speech to text apps available now are amazing.

One of the big concerns, always, is that people who cannot use standard telephone technology, have the option of calling 911 in the event of an emergency. There has always been concern about having 911 relay available. I hope that someone who uses 'relay' will chime in here. I have always been able to hear fairly well on the phone as long as I can use the telecoils in my hearing aid and cochlear processor, so have not needed to use relay. Years ago, I did use a TDD to communicate with friends who needed to use it.