Frequent Asked Questions

What is Real-Time Text?

Real-Time Text is a feature that allows users to see text as it is typed into a text interface. It differs from Internet instant messaging (IM) and mobile texting (SMS) in that the characters appear in near real-time as they are typed or created, not as a block of text after it is written. Real-Time Text is communicating using text that is the closest to voice communication.

What can Real-Time Text be used for?

Real-Time Text can be used on its own to enable conversations using text. It can also be used where voice is impractical (such as in noisy environments or meetings), or as an adjunct to voice and video conversations to transfer text information with the audio or video feed. Real-time transcription of a video or audio conference is an example.

Real-Time Text is part of a concept called “Total Conversation” which provides bi-directional real-time exchange of video, text and voice between users in two or more locations.

What is Total Conversation?

Total Conversation is a service allowing an audiovisual conversation with bidirectional full-duplex real-time transfer of Real-Time Text, Video and Voice between 2 or more users.

Total Conversation allows people with a disability (deaf or hard of hearing or blind for example) and people who find themselves in a situation where the complementing streaming media Real-Time Text, video and Voice together fulfills the conversation needs much better than only Voice (background noise, being in a library etc).

Total Conversation is an ITU service description in ITU-T Rec. F.703.

Why is Real-Time Text important to people who are deaf or hard of hearing?

In addition to its many applications for fully hearing people, Real-Time Text is important as an equivalent alternative to voice communications for people who are deaf and hard of hearing. It allows a more natural, bi-directional flow of text based conversation to take place compared with the “type-enter-wait-read-response-reply” technology of IM(chat) and SMS.

In fact: when Real-Time Text is fully mainstream, it will be solving one of the biggest accessibility problems of Internet communications for people who are deaf or hard of hearing!

What is the technology behind Real-Time Text?

At the core of the framework for Real-Time Text over Internet Protocol (IP) networks is the Session Initiation Protocol (SIP) and the Real-Time Text transport standard as currently described in IETF RFC 4103.

This framework is designed to be compatible with voice over IP (VoIP) and Video over IP environments. It also builds upon, and is compatible with, the high-level user requirements of deaf, hard of hearing, and speech-impaired users, as described in RFC 3351.

What was the Real-Time Text Taskforce?

The R3TF was a centre for advocacy and knowledge exchange in the field of real-time text. It contributed to the promotion, design and implementation of interoperable RTT solutions and encourage adoption of RTT in mainstream products and services.
The R3TF was also an Accessibility organisation for people who are Deaf, Hard of Hearing or have a speech impairment, since RTT will make Telephony over Internet fully accessible for everybody and this fits in the "Design for All" approach. The R3TF had as goal to make Real-Time Text mainstream and part of universal design, so that all people can communicate with each other without difficulty or limitations or having to use expensive assistive telecom equipment like a text telephone.

The website RealTimeText.org is taking over all the information and promotion activities of the R3TF per october 1st 2014.

What can we do to help the website RealTimeText.org?

We can use a webdesigner to assist us in the design of a new and more modern website. And good writers helping to update the content and make it more readable for all people, companies and organisations interested in Real Time Text and Total Conversation.

What is the relationship between Internet Society and the Real-Time Text Taskforce till October 1st 2014?

ISOC has launched an Enabling Access initiative which aims to address some of the fundamental impediments to Internet growth and usability.

One aspect of the initiative focuses on advancing the development of technologies, the business case, and policy environment for facilitating the use of the Internet by people with disabilities. As part of this effort, ISOC has served as an “incubator” of the R3TF by providing coordination assistance, technical expertise, and implementation support for the Taskforce.

Now that the R3TF is an independent foundation until October 2014. The R3TF and ISOC worked together to archive the goals of the R3TF. And ISOC has been one of our sponsors.

What is the difference between ToIP and Real-Time Text?

ToIP is RFC4103, which is Real-Time Text on IP networks using SIP.

Real-Time text is text transmitted instantly while it is being typed or created. The recipient can immediately read the sender's message as it is written, without waiting. Real-Time Text is possible using different standards and protocols.

If Real-Time Text appears to be "character by character", does every character always use 1 packet?

Absolutely not. For example; Real-Time Text for SIP as described in RFC4103 samples the text for every 300 millisecond. So, there will be multiple characters in one UDP packet in that case. Moreover, when nothing is typed, no RTP packets are sent (except for session keep-alive), while voice keeps sending packets even if there is silence.

What is the expected bandwidth usage of Real-Time Text in a SIP call (RFC4103)?

About 2 kbit/s. That is  2.5% of the bandwidth of the most common audio codec G.711 with 50 packets/sec at 80kbit/s.

The calculation asumes the maximal human typing speed of 120 words per minute:
120 wpm = 600 char/minute = 600 bytes/minute (because UTF-8 coding for western/latin languages like Spanish and English has 1 byte per char )  = 10 bytes /sec
RFC4103 uses 300 ms buffering/ time sampling, so it sends about 3 packets per second = 30 bytes per second.
With 3 packets, with an overhead by RTP of about 60 bytes per packet. = 180 bytes, To be save say 200 bytes.

200 bytes RTP overhead + 30 bytes in characters = 230 bytes divided over 3 packets per second.
230 bytes= 1840 bits per second = 1.84 kbit/s

Is there a higher risk in miscommunication and/or confusion when using Real-Time Text compared to chat/Instant Messaging?

No, not at all. There is no proof that there is more miscommunication due the real-time nature of Real-Time Text. In fact, just like with speech, the users can immediately interrupt the conversation and ask for clarification.