Clarity and Uniden phones are among the top-ranking phones for the hearing impaired. Phones are available in several categories for different levels of impairment ranging from mild to moderate hearing loss, up to severe loss and deafness.
Mild to moderate hearing loss generally requires a phone with at least 20 decibels of amplification, while moderate to severe loss requires 50 decibels. Severe to total loss requires units capable of manual text entry and converting incoming voice transmission into visual text. These models are called TTY and captioned telephones, some of which have visual text displays while others provide a printout of the conversation.