Most Deaf and Hard of hearing people use the same methods to communicate as the hearing world, like texting and video chats, (closed captioning is also commonly used). However, there have been a handful of specific devices created solely for the Deaf community. Below are a few examples.
TTY, or teletypewriter is a device that allows for the use of the telephone without needing to speak. Instead the user can type out messages which are sent back and forth between the two users. In order for a TTY to be used both ends must have one set up. This version of communication created in the mid 1960’s was one of the first ways for Deaf and hard-of-hearing people to communicate with phone lines, but it is less generally used in society now.
Text relay, this service is for communication between a hearing person and someone whom is deaf or hard of hearing. The hearing person will call the deaf person with a normal phone and speak into it. An operator on the other end will then type out the message and send it to the deaf individual. The deaf person can then reply by typing out a message, which the operator will tell the hearing individual. This from of communication is speech-to-text and text-to-speech, and only works when internet is available.
Video phoning is highly popular, with the allowing of direct communication through sign language back and forth, as well as the ability to leave a message. Many companies offer different versions of the phones, and some supply deaf individuals with the equipment for free. This form of communication requires internet as well.
Many Deaf people will connect lights to flash when a doorbell is pushed, or a phone or alarm goes off. The light flashes achieve the same purpose of notifying that someone is there, or something is going off. While not exactly a device created for the Deaf community, it is something that has been helpful.