The National Emergency Number Association, in conjunction with telecom testing company TelecomXchange International, has developed a system, known as TTY-PASS, to ensure that equipment used by 911 centers to communicate with deaf or hearing-impaired callers is accurately working.

TTY-PASS works sends out a three-minute test script to the 911 operator’s TTY, where the public safety access point then copies the text into a secure Web site and is given a score. To receive a passing score, the TTY must have a one percent or less total character error rate.

The automated system was created to help 911 centers fulfill the standards set by the Americans with Disabilities Act (ADA), which mandates every emergency operator have access to text-based telecommunications devices for the deaf (TTYs or TDDs) and requires regular testing of such equipment.