To ring up the deaf people have a particular device called "Telephone Device for Deaf" . The first TDD were connected to the home telephone by a receiver, now it is a dedicated equipment with a display and a keyboard like a computer, and it can only be connected with other TDD.
When the telephone rings, a light connected to TDD flashes, you can answer by pushing the bar-space and you begin to write on the small screen. On the screen you can read the words written by the other person that called you.
When one of the two person has finished to write he fingers ** and close the conversation with *************.

The TDD is a "written telephone" and it is also portable, very easy to connect also to public phone. Beyond of TDD, now are available the mobile phones used by deaf to send short SMS messages.
Internet too has permitted to knock down some communication's barriers.