IP CTS, TTY and RTT, in plain English
The US relay landscape is full of acronyms designed for a landline world. Here's what each one actually is, and where a modern captioned calling app fits in.
TTY (teletypewriter)
TTY is the oldest form of relay: a keyboard-and-screen device that sends typed text over a phone line. It works, but it requires special hardware, both parties often need compatible equipment, and the experience is nothing like a normal phone call.
RTT (real-time text)
RTT replaces TTY over modern cellular networks. Text is transmitted character-by-character as it's typed, so the receiver sees the conversation forming in real time. Supported by iPhone and most Android phones, useful, but it requires the other person to type instead of speak.
IP Relay
IP Relay uses a human communications assistant who reads the Deaf user's typed messages aloud to the hearing party and types the hearing party's spoken words back. Free, federally funded, but introduces a third-party listener.
IP CTS (Internet Protocol Captioned Telephone Service)
IP CTS is the category Rogervoice is certified under. You speak on the phone normally; the other person's speech is captioned to your screen. Federally funded for eligible US users with hearing loss, and, in Rogervoice's case, delivered by AI with no human listener.
Frequently asked
What's the difference between TTY and RTT?
TTY is the legacy standard using dedicated hardware over analog phone lines. RTT is the modern equivalent, built into iPhone and most Androids, that streams text over cellular data as it's typed.
What is IP CTS?
IP CTS is Internet Protocol Captioned Telephone Service. Certified providers use the internet to deliver real-time captions of a phone call to users with hearing loss. In the US, the service is funded through the FCC's TRS program.
Is a captioned calling app a relay service?
Captioned calling under IP CTS is legally part of the FCC's Telecommunications Relay Service program, but the user experience is nothing like traditional relay: no third-party operator types for you, the call stays a normal voice call, and captions appear directly on your screen.
Captions that keep up with you.
Free, FCC-certified captioned calling on the phone you already own.