This information is provided as a service to PSAPs & 911 call-takers to help correctly identify & respond to CapTel/VCO calls. Each PSAP should refer to its own standard operating procedure for VCO when responding to calls.

What is CapTel?

The Captioned Telephone (“CapTel”) is a new telephone that allows deaf and hard of hearing people to receive both the voice and written captions of what the other party in a phone call says. The captions are supplied by a TRS service for all non-9-1-1 calls. The CapTel user uses their own voice to talk directly back to the other party.

What happens when a CapTel user dials 9-1-1?

When a CapTel user dials 9-1-1, the CapTel phone calls 9-1-1 directly (it does not route through the TRS service). This means the caller accesses 9-1-1 directly, but will not receive word-for-word captions. The CapTel phone also automatically converts into a Voice Carry Over (VCO) phone.

What do 9-1-1 PSAPs need to do?

The call-taker needs to respond by following the same procedure used for handling VCO calls. Basically, the call-taker needs to communicate by typing messages to the CapTel user on a TTY, and then listening to the CapTel user talk back by voice. The call-taker’s typed TTY messages show up in the display of the CapTel phone. The CapTel user does not have a keyboard, so they cannot type TTY messages back to the call-taker. They can only use their voice to talk to the call-taker. Thus the conversation is half in text (TTY) and half in voice.

VCO call handling capability is currently required of all 9-1-1 PSAPs by the US Department of Justice and thus the CapTel phone operating in VCO mode does not represent a new requirement for 9-1-1 PSAPs which should already have existing standard operating procedures (SOP) to handle VCO calls.

What equipment do you need?

The call-taker must be equipped with a TTY. The TTY should be set up so that switching between TTY and audio (voice) mode is easily done. Switching between TTY transmission and listening to voice from the caller must be done each time the conversation switches from the call-taker (who is typing on a TTY) to the caller (who is speaking over the telephone handset).

How many CapTel phones are out there?

There are several thousand CapTel phones now in service in the USA. The FCC has recently approved CapTel as part of the Telecommunication Relay Service (TRS) which will cause the number of CapTel phones to increase substantially. Federal agencies have opted for CapTel service making CapTel available in every state. A substantial increase in the number of CapTel users, nationwide, is expected.

Additional Information on CapTel

The following background information about CapTel is provided as a service to PSAPs.


What is CapTel?

CapTel is a combination voice and text telephone designed specifically for people with hearing loss. It looks and works just like a regular telephone, with one important difference: the telephone displays word-for-word captions of everything the other party says on a built-in display screen. Users can also hear the other party with whatever residual hearing they may have. They receive both the voice and written captions of the conversation.

How does CapTel work?

For non-9-1-1 calls, the captions are provided by a telecommunications relay service (TRS), which listens in on the call and transcribes everything the other party says into written text. When a CapTel user places a call, their call is first routed through the TRS service, then connected to the end telephone number. Captioning assistants (CAs) at the TRS service use the very latest in voice-recognition technology to provide extremely accurate captions in near real time. Their participation is transparent to both parties in the conversation.

Who uses CapTel?

CapTel users typically fall into one or more of the following categories: 1. Senior citizens and persons with significant hearing loss. 2. Late deafened individuals accustomed to using the telephone. 3. Hearing aid and cochlear implant users of all ages. 4. Individuals who are deaf and have speech skills.

How many CapTel Users are there?

At this time, there are several thousand CapTel users in the United States. This number is expected to grow rapidly because CapTel has recently been approved by the FCC as an enhanced form of VCO which may now be included as part of the TRS relay system. Many states and federal agencies have recently contracted for CapTel service starting in early 2004.

CapTel Calls To 9-1-1

How a CapTel phone makes calls to 9-1-1

In order to provide CapTel users with the most reliable and fastest possible access to 9-1-1 service, 9-1-1 calls dialed on a CapTel phone are not routed through the TRS captioning service, but instead go directly to the most appropriate PSAP just like any other telephone would place the call. This ensures that the CapTel user will receive the benefits of calling 9-1-1 directly, including the fastest possible access to the most appropriate PSAP, immediate telephone access to a 9-1-1 call-taker, and automatic number identification (ANI).

This means, however, that the CapTel user will not receive captions from the TRS service. Instead, as soon as 9-1-1 is dialed, the CapTel phone becomes a Voice Carry Over phone and the incoming call to 9-1-1 must be handled as a VCO call.

Basics of CapTel 9-1-1 Calls

In a CapTel 9-1-1 call, the CapTel user speaks directly to the 9-1-1 call-taker, but may not be able to hear what the call-taker says. The 9-1-1 call-taker must then type messages back to the CapTel user using a TTY (or TTY-equivalent device that transmits in Baudot code), then listen for a spoken response from the CapTel user. The CapTel user reads typed messages from the 9-1-1 call-taker, and then responds by speaking over their phone.

It is important to note that the CapTel user does not have a keyboard to type on. The only way the CapTel user can communicate to the 9-1-1 call-taker is to speak with their voice.

An incoming CapTel phone call requires that 9-1-1 call-takers correctly identify the call as a VCO call (not a TTY call). To handle the call, the 9-1-1 equipment must be capable of easily moving back and forth between TTY mode and audio (voice) mode.

How a 9-1-1 CapTel call progresses

When a CapTel user dials 9-1-1 on a CapTel phone, the following sequence of events takes place:

  1. The CapTel call comes in to the 9-1-1 call-taker the same way it would for any voice call. The 9-1-1 call-taker will be able to hear the CapTel user, as well as any background noises.
  2. Depending on the CapTel user’s level of hearing loss, the CapTel user may be able to hear the 9-1-1 call-taker well enough to continue the call as a “normal” voice telephone call. In that case, the 9-1-1 call-taker follows the normal operating procedure for any standard voice call.
  3. If the CapTel user cannot hear well enough to understand the 9-1-1 call-taker:
    • The CapTel phone display instructs the user to ask for “captions” by pressing a button on the CapTel phone. Upon pressing the button, the CapTel phone converts to a VCO phone.
    • The CapTel phone automatically sends a TTY text message to alert the 9-1-1 call-taker to the need for VCO (TTY one way, voice the other way) communication. Every eight seconds the CapTel phone sends a message similar to “VCO GA”. This TTY message may trigger TTY detection equipment at the call-taker’s station.
    • The automatic “VCO GA” message is repeated every eight seconds until the 9-1-1 call-taker responds by typing on a TTY. The 9-1-1 call-taker should type a message to the CapTel user such as: “911 HERE GA” or “9-1-1 HERE WHAT IS YOUR EMERGENCY GA”
    • The CapTel phone will then automatically send back a TTY message to confirm that the 9-1-1 TTY message has been received and to explain how the call should be handled. The CapTel phone will send a message similar to: “USE VCO YOU MUST TYPE TO ME ON TTY I WILL TALK TO YOU BY VOICE GA”
    • It is important to note that even though the CapTel phone has sent an automatic message using TTY code, the CapTel user does not have a keyboard and cannot type messages back to 9-1-1. The CapTel user can only use their voice to talk to 9-1-1 at all times.
    • The 9-1-1 call-taker should leave the audio on throughout the call (except when the TTY messages are being transmitted) in order to hear what the caller is saying by voice.

Responding to a CapTel (VCO) Call

Each call center should have an established SOP for handling VCO calls. General guidelines for handling VCO calls include:

I. Identifying an incoming call as a VCO call

  • Call-taker will be able to hear the VCO user, but the VCO user cannot hear the call-taker.
  • CapTel user may identify themselves as a VCO user, a CapTel user, or a hard-of-hearing individual
  • Call-taker may receive a text message (Baudot tones) identifying the call as a VCO call.

II. Establishing communication with the VCO user

Upon identification of the call as a VCO call, the call-taker should:

  • Switch to TTY mode or transfer the call to a TTY capable station.
  • Type a brief message to the VCO user on a TTY. For example, “911 HERE WHAT IS YOUR EMERGENCY GA”. The message should end with “GA” (meaning GO AHEAD”) to notify the VCO user that it is their turn to talk.
  • Leave audio-(voice-) mode on or switch to audio-mode whenever the TTY is not transmitting so that you can listen for the VCO user’s spoken response.
  • Any questions the 9-1-1 call-taker has should be typed to the VCO user on a TTY.
  • The 9-1-1 call-taker will not be able to hear the VCO user when TTY text is being transmitted from the 9-1-1 call-taker to the VCO phone.
  • VCO communication requires frequent switching between TTY-mode and audio-mode.

III. Communicating with a VCO User

  • The call-taker must listen to the VCO user’s voice.
  • When the VCO user is finished speaking, the call-taker should switch to TTY mode and type questions and instructions to the VCO user. The call-taker should type “GA” when finished to alert VCO user that it is their turn to talk. The call-taker will not be able to hear the VCO user’s voice when typing a message on the TTY.
  • When not typing on the TTY, the call-taker must switch back to audio-mode and listen to the VCO user’s voice. VCO users may or may not say “Go Ahead” or “GA” to indicate when they are done talking. The call-taker should use normal conversational skills to determine when they should send a TTY message to the VCO user.
  • Continue this process, taking turns typing and listening, throughout the duration of the call.
VCO User can: VCO User cannot:
1. Talk directly to emergency service call-taker. 1. Hear what the call taker says over the phone.
2. Read any text messages that the emergency service call-taker types on a TTY. 2. Type messages back to the emergency service call taker.
3. Interrupt the emergency service call taker when text is being transmitted.

Recommendations for 9-1-1 Call Centers:

  1. Review and maintain your center’s written SOP for receiving and responding to VCO calls from users of VCO telephones.
  2. Review and maintain your center’s written SOP for “silent” open line calls to ensure that call-takers will consider a “silent” open line as a potential TTY or VCO call and will query the “silent ” open line with a TTY.

Equipment Recommendations

  1. Ensure that each manned call-taking position is equipped with its own TTY accessible equipment.
  2. Maintain or modify existing equipment to enable call-takers to switch between and/or simultaneously engage in voice and TTY communication for VCO calls.
  3. Continue to maintain a separate, stand-alone TTY to ensure that backup equipment will be provided in case of a malfunction.
  4. Establish a regular maintenance schedule for all TTY-related equipment.

Training Recommendations

  1. Provide comprehensive training for every 9-1-1 call-taker including:
    • General information about Title II of the ADA
    • General information about communication issues regarding individuals who are deaf or hard of hearing
    • Practical instruction on identifying and processing VCO and TTY calls, including the importance of using the proper syntax and protocol when responding to VCO and TTY calls.
  2. Provide a refresher training course every six months in order to maintain call-taker’s skill levels.
  3. Establish and maintain a working relationship with the deaf and hard of hearing community in order to continue to evaluate the services, practices, and procedures that relate to 9-1-1 call handling.

Additional Resources:

U. S. Department of Justice. Americans with Disabilities Act: Access for 9-1-1 and Telephone Emergency Services. From

TDD/TTY Accessibility Checklist for PSAPs. From

U. S. Department of Justice. (1993). Title II Technical Assistance Manual. From

U. S. Department of Justice. (1994). Title II Technical Assistance Manual 1994 Supplement. From

Toni D. Dunne (1997) Acronym Soup. APCO Bulletin, January.

ADA Requirements DOJ technical assistance documents about TTY/VCO requirements