Telecommunications Relay Service
Telecommunications Relay Service, also known as TRS, Relay Service, or IP-Relay, is an operator service that allows people who are Deaf, HardofHearing, SpeechDisabled, and DeafBlind to place calls to standard telephone users via TDD (TTY), personal computer or other assistive telephone device.

# Types of service available
Depending on the technical and physical abilities of users different call types are possible via relay services.

## TTY to Voice/Voice to TTY
The most common type of TRS call, involves a call from a person who is Deaf and utilizes a TTY to a person who is Hearing and does hear and speak.  In this call type, typed messages are relayed as voice messages by a TRS operator (OPR) (also known as Communication Assistant (CA), Relay Operator (RO), Relay Assistant (RA) or Relay Agent (Agent) ), and vice-versa.  This allows callers unable to use a regular telephone, to be able to place telephone calls to people who use a regular telephone, and vice-versa. When the person who is Hearing is ready for a response, it is customary to say "Go Ahead" or "GA" to indicate that it is the TTY user's turn to talk and "Stop Keying",  "SK", or "Ready to hang up" when hanging up, and vice-versa.

## Voice Carry Over
The next most common call type is Voice Carry Over (VCO). VCO allows a person who is HardofHearing or Deaf and does speak to use one's voice while receiving responses from a person who is Hearing via the operator's typed text. There are many variations of VCO, including 2-Line VCO and VCO with privacy.

### VCO with Privacy
The operator will not hear the VCO user's voiced messages and the VCO user does not need to voice GA. The operator will hear the person who is Hearing, and the person who is Hearing must give the GA each time to alert the operator it is the VCO user's turn. The VCO user does not need to voice GA, because the VCO user types it or presses the "VCO GA" button on the VCO phone when it the voice user's turn to talk.

### 2Line VCO
2-Line VCO allows a VCO user using a TTY or computer to call a TRS operator, who in turn calls the VCO user on a second telephone line, which serves as the voice line. The user puts the operator on a brief hold to initiate a 3-way call with the Hearing person. This method is frequently used by people who are Hard-of-Hearing and like to use some of their residual hearing as well not having to say "Go Ahead". With 2Line VCO, the VCO user and the voice user can interrupt each other. VCO with Privacy cannot be used with 2Line VCO, because the operator, VCO user, and Hearing person are on a 3way call.

## Hearing Carry Over
A less common call type is Hearing Carry Over (HCO).  HCO allows a person who is SpeechDisabled and can hear to use one's hearing while sending responses to a person who is Hearing via the HCO user's typed text. The operator voices the HCO user's typed messages, and then the HCO users picks up the handset and listens to the other voice user's response. There are many variations of HCO, including 2-Line HCO and HCO with privacy.

### HCO with Privacy
The operator will not hear the voice user's voiced messages and the voice user does not need to voice GA. The operator will voice for the person who is SpeechDisabled, and the person who is SpeechDisabled must give the GA each time to alert the operator it is the voice user's turn. The voice user does not need to voice GA, because the HCO user can hear when the voice user finishes talking. VCO with Privacy cannot be used with 2Line VCO, because the operator, HCO user, and Hearing person are on a 3way call.

### 2Line HCO
Similar to 2-Line VCO, 2-Line HCO allows an HCO user using a TTY or computer to call a TRS operator, who in turn calls the HCO user on a second telephone line, which serves as the voice line. The user puts the operator on a brief hold to initiate a 3-way call with the Hearing person. This method is frequently used by people who are SpeechDisabled and like to use some of their residual speech as well not having to type "GA". With 2Line HCO, the HCO user and the voice user can interrupt each other.

## Speech to Speech
Speech to Speech (STS) exists for people who have speech disabilities. A speciallytrained STS TRS operator revoices what the person with a speech disability says. STS is often used in combination with VCO for people who are Deaf and have somewhat understandable speech, as well as 2Line HCO users. STS enables people with speech disabilities to call others (able-bodied speakers and other people with speech disabilities). It also enables people without speech disabilities to call people with speech disabilities. Anyone can call 711 and ask for Speech to Speech. STS is also available in Australia, New Zealand and parts of Sweden.
Many STS users have Parkinson's disease, cerebral palsy, ALS, multiple sclerosis, muscular dystrophy or stroke.  Other users stutter or have had a laryngectomy. STS also helps speech synthesizer users, users of Augmentative and Alternative Communication (AAC.)  AAC users can set their device next to a speakerphone.  They ask the STS CA set up the call, negotiate the menu, introduce the call explaining AAC and then go into the background.  This enables AAC users to communicate independently once the other party is on the line. For more information visit .

## DeafBlind variation
Telebraille also exists for people who are DeafBlind with the use of a TTY with a braille or regular keyboard and a refreshable braille display or LVD (Large Visual Display). A relay call of a user who is DeafBlind is directly related to a relay call of a TTY user, however, the text transmission speed is often reduced to increase the ability of the user who is DeafBlind to comprehend the moving braille on the braille TTY or large print on the LVD. Telebraille relay operators must be familiar with Braille contractions that users who are DeafBlind may use. Some TTY users with mobile disabilities may prefer to use a Telebraille, due to the smaller keyboard, regardless of a sight disability or lack thereof.

## Captioned telephone
A new method for people who are Hard-of-Hearing, Oral Deaf or LateDeafened to make phone calls is called a  captioned telephone (also called captioned relay or Cap-Tel). It is a telephone that displays real-time captions of the current conversation.  The captions are typically displayed on a screen embedded into the telephone base.  A captioned telephone may also be called a CapTel, which is the main brand name for a captioned telephone. A CapTel can also function exactly like a VCO by switching the device to VCO mode, for example, to communicate with an HCO user directly, without relay.
Captioned telephones use a stenomask system by a remote operator, similar in fashion to closed captioning of live TV shows. Presently (2007), stenomask voice recognition with a regular keyboard is the only method used for captioned telephone systems.
While this service is similar to 2Line VCO, it only requires one telephone line, but privacy is inherent, since the CapTel captioner cannot hear the CapTel user. Unlike TTY, VCO, HCO, and STS relay, CapTel only available to people in states that have CapTel as part of their relay service, because the FCC has not mandated CapTel captioning service. CapTel is available in every state and federal territory, for federal/military employees/contractors (active or retired) and Native Americans.

### 2Line CapTel
2Line CapTel can also be used with 2 lines. This is especially useful for users who prefer to give out their home phone number alone, instead of both the captioning service number and the toll-free captioning service number or for users who prefer to turn captions on and off anytime during the call. 2Line CapTel can also be used with other relay services. For example, STS can be used with 2Line CapTel, for CapTel users with speech disabilities. 2Line CapTel is only available to people in states that have 2Line CapTel as part of their relay service or federal employees/contractors and Native Americans.

### CapTel USB
CapTel users who are Blind or LowVision use CapTel USB, connecting directly to a computer to display conversation captions on a computer screen or refreshable braille display, via a USB cable. CapTel USB users enjoy large print or braille captions throughout CapTel phone conversations. CapTel USB users can control the size, color and font style of the captions on the computer screen for easiest reading and save and print/emboss conversation captions on their computers.

## Other variations
Many other call type variations are possible, including VCO to VCO, HCO to HCO, HCO to TTY, and VCO to TTY. Fundamentally, relay services have the ability to connect any two callers with different abilities over the telephone network.

## Internet relay service
There are internet relay services that provide functionality similar to TTY to Voice services, replacing the TTY and telephone line with a specialized computer program and internet connection.  There are multiple types of computer programs that can be used including custom Java based programs that run in the users web browser and instant message based services.
Since it is not possible to identify the exact location of a caller using an internet service, the relay operator will ask for the street address, city, and state that the call is originating from when requesting a call to 911. If this information is not provided then the operator will be unable to process the call.

## Video Relay Service
Video Relay Service (VRS), allows people who use Sign Language are able to place phone calls by signing instead of typing.  The VI (video interpreter) uses a webcam or videophone to voice the Deaf or Speech-Disabled person's signs to the Hearing person and sign the Hearing person's words to the Deaf or Hard-of-Hearing person.

# Accessibility
As much of the TRS system, particularly the Internet Relay Services, is open for public use; it is possible for anyone with the proper equipment to place calls. This includes people who are not members of the original intended user group, who are Deaf, Hard-of-Hearing, or SpeechDisabled. Some such users have noted its usefulness in making long-distance or local calls free of charge and without a telephone. Providers defend the accessibility even to people who have neither hearing nor speech disabilities as a necessary evil. This is because the principle of "transparency" - the belief that the operator and the mechanics of relay should generally go as unnoticed as possible in the call - requires that relay be as easy to use as a normal telephone, which does not require any kind of verification for Hearing people to use. Leaders in the Deaf community defend this decision and generally retain strong support among service users with hearing and speech disabilities.

# Fraudulent uses
The open structure of relay services has led to a number of complaints regarding its use as a vehicle for fraud. In 2004, news outlets such as MSNBC and the Arizona Daily Star ran stories of reported abuse of the relay system, such as users from international locations calling businesses in the United States to fraudulently purchase goods. This has also generated numerous complaints, particularly by those who were employed as relay operators, that so-called "prank calls," where neither user requires the service and the caller is just attempting to have fun with a novel mode of communication. In December 2006, NBC ran another story where former operators alleged that "85 to 90 percent" of calls were scams.  Since it is illegal for relay service companies to keep records, fraudulent users can operate with impunity.  Fraudulent calls of both types have been cited as reasons for further relay regulation, and as causes for long hold times that must be endured by many legitimate users.
In 2006, the FCC has launched a campaign to gather feedback from the various Internet Protocol relay-certified companies operating within the United States to fight the wave of relay scams and pranks being made over the service. As brought up in the FCC's released document, users on the IP-based relay services can thus place their calls anonymously, which cannot certify that the user in question really needs operator assistance or not. Furthermore, fraudulent calls of any nature cost millions to the American people yearly, based on the $1.312 per minute fee that is being paid to various relay providers for completed calls.