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Elderly man using Hearing Carry Over service.

Hearing Carry-Over (HCO)

800-735-2966 for English
800-520-7309 for Spanish

Hearing Carry-Over (HCO) is the ideal solution for you if you want to listen and type on your phone calls. You type on your text telephone/teletypewriter (TTY) or VCO/HCO phone and the communications assistant reads your words aloud to the other party.

This service is designed for people with speech difference.

This relay service is available in English-to-English, Spanish-to-Spanish and Spanish-English/English-Spanish Translation.

The TRS Customer Profile allows you to store your relay call preferences and helps speed up call processing.

How Does Hearing Carry-Over (HCO) Relay Work?

It’s a cinch!

Just dial 711 (or 800-735-2966 for English, 800-520-7309 for Spanish-to-Spanish or Spanish-to-English/English-to-Spanish Translation) on your text telephone/teletypewriter (TTY) or VCO/HCO phone and the relay operator will answer with “Relay Missouri”.

Type the area code and telephone number you wish to call and type “GA” (“Go Ahead”). The communications assistant will dial the number and connect to the other party.


Type your message on your TTY or VCO/HCO phone to the communications assistant.  Type “GA” (“Go Ahead”) at end of each message.  The “GA” indicates that it is the other party’s turn to respond.


The communications assistant reads your typed message aloud to the other party.


The other party listens and speaks directly to you.  The other party says “Go Ahead” to indicate that it is your turn to respond.

To conclude the call, type “GA to SK” (“Stop Keying”) to indicate that you are ready to hang up.

Collage of images describing the steps for Hearing Carry Over services.

Video: How does a Hearing Carry-Over (HCO) call work?

Here’s how an HCO user, Don, communicates with a standard phone user named Dennis at an auto shop.

Other HCO Features

Please specify to the communications assistant the HCO call type you would like to make.


You, the HCO user, listen while the communications assistant reads aloud the TTY user’s typed words. You type directly to the TTY user.


The communications assistant reads aloud both of the HCO users’ typed words.

T-Mobile IP Relay Two-Line HCO

T-Mobile IP Relay’s Two-Line HCO allows a person with a speech disability to listen and type their conversation while the Relay Operator reads aloud to the other party.

Download IP Relay Two-Line HCO PDF