Communication devices are tools used to facilitate communication between two or more people. Two common examples of communication devices are TEL (3 letters) and TTY (3 letters). TEL stands for Telecommunication Device for the Deaf, which is a device that allows people who are deaf or hard of hearing to communicate over the telephone. TTY stands for Text Telephone, which is a device that allows people to communicate with each other using text messages. Both of these devices are important tools for people with hearing impairments to stay connected with the world.