What Is TTY Mode on Cell Phones?

By William Lynch

Updated August 29, 2017

Most cell phones come equipped with a TTY mode for the hearing impaired.
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Cell phones have so many features, it can be tricky to figure out what they all do. One of the more mysterious options for some is the TTY mode. The TTY abbreviation stands for teletypewriter, a device that allows deaf or hearing-impaired individuals to communicate via the telephone by typing text messages. Cell phones with a TTY mode are compatible with this technology and perform the same service after they're connected to a TTY device.


While the telephone revolutionized communication following its invention during the late 1800s, deaf individuals could not benefit from the technology until Robert Weitbrecht invented the teletypewriter in the 1960s. The original TTY machines used an acoustic coupler to hold the telephone handset receiver and recycled teletype machines to transcribe the incoming messages. TTY relay services emerged to spread the technology, serving to convert voice-to-text and text-to-voice communications for individuals without TTY machines. Today, the Federal Communications Commission requires all cell phone manufacturers and service providers to make their phones as accessible as possible for the hearing impaired, leading to the inclusion of TTY modes.


Various manufacturers produce lightweight, portable TTY devices that perform all the same functions as a traditional teletypewriter. Not much larger than a cell phone, these portable TTY devices run on rechargable batteries and typically feature a four-row keyboard for text entry and a two-line LCD screen for text display. The portable TTY device connects to the phone via a cable using the cell phone's audio jack.


Before enjoying the benefits of TTY mode, you must first activate the option from your cell phone's menu. After activation, connect the cell phone to the portable TTY device via the cable and corresponding audio jacks. Turn on the TTY device and then dial the number on your cell phone as normal. After the connection is made, use the TTY machine to enter and to receive your text messages like a normal TTY phone call.

Smartphone TTY Support

Modern smartphones support TTY as well as older phones. Consult your phone's manual or manufacturer to learn how to enable TTY mode. Apple iPhones running iOS 10 or later support a built-in TTY feature that requires no external equipment. And some communication and conference calling apps also support TTY mode, even if they're not using traditional phone connections.


Even though it is similar to text messaging, your cell phone's TTY mode provides the ability for a continuous conversation without the constant interruptions of sending and receiving texts. In a TTY conversation, one party types a message and it immediately appears on the other party's TTY screen without losing connection. Using a cell phone and portable TTY device provides the freedom to make a TTY phone call from anywhere at any time, which can be particularly important during emergencies.


When making a TTY call with your cell phone, keep the cell phone and the TTY device at least 18 inches apart to avoid potential radio frequency interference. Also, when purchasing a new cell phone, look for the TTY symbol on the phone's packaging and confirm that your service provider is TTY compatible and supports TTY tones.