Text Standards

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Accessible real-time conversational service:
Summary of overviews, specifications and standards.

Gunnar Hellström, Omnitor
May 25, 2006

This is an overview of specifications related to accessible real time conversation, including Total Conversation and Text Telephony. The reader must be aware of that the work in the standards groups move on, and new versions of the referenced specifications may take effect. For implementation, only the versions retrieved directly from the standard bodies shall be used and verifying that the version is valid.

Some overviews and presentations are also included.

For 3GPP, the specifications can be found in the "Document area" under www.3gpp.org

For ITU-T, the recommendations can be found under http://www.itu.int/ITU-T/publications/recs.html .

For IETF, the specifications can be found under www.ietf.org .

For ETSI, the specifications can be found under www.etsi.org .

All 3GPP specifications related to text telephony and total conversation are accepted as ETSI technical specifications and are listed under ETSI below.

Overviews, articles, regulations, policy statements

*Document*	*Full name*	*Explanation*	Type
COCOM 04-08	INCOM Report	Report on eAccessibility to EU regulatory group COCOM	Priority action requirements
TCAM 17(64)	TCAM eAccessibility	Request to TCAM for terminal related action for accessibility	action request from EC
TCAM 17(64) presentation	TCAM eAccessibility	Presentation to TCAM 17 on real time conversation needs	Powerpoint presentation
ITU-T Web pages on Accessibility	ITU-T SG 16 Work on Accessibility	Summary of work in ITU-T Multimedia group and related	Web site
Accessibility presentation in IMTC-NGN workshop	Accessibility in New Emerging Networks and Services	Presentation made for joint ITU-T / IMTC workshop 2006	PDF of Powerpoint

Standards and specifications

IETF accessibility specific documents

*Standard*	*Full Name of Standard*	*Explanation*	Type	Status
IETF RFC 4102	Registration of text/red	MIME registration of text with redundancy	MIME reg	Approved
IETF RFC 4103	RTP Payload for Text Conversation.	RTP Payload for T.140 text conversation. MIME Registered as "text/t140", used in H.323 and SIP and 3GPP	Transport	Approved replaces RFC 2793
draft-ietf-sipping-toip-04	Framework of requirements for real-time text conversation using SIP		Requirements	Draft
IETF RFC 3351	User Requirements for the Session Initiation Protocol (SIP) in Support of Deaf, Hard of Hearing and Speech-impaired Individuals	Handles transcoding and other value added services invoked through SIP.	Requirements	Approved
draft-ietf-sipping-transc-conf	The session Initiation Protocol Conference bridge transcoding model	Mentioned that it can be used for invocation of relay services	Procedure specification	Draft
IETF RFC 4351	RTP Payload for Text Conversation interleaved in an audio stream	RTP Payload for text, intended for transit gateways where number of ports may be an issue.	Transport	Approved.

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IETF General documents of specific interest for accessibility

*Specification*	*Title*	*Explanation*	*Type*	*Status*
IETF RFC 2327	SDP; Session Description Protocol	Parameters and formats for call setup in SIP	Call control	Approved
IETF RFC 3261	SIP; Session Initiation Protocol	Session initiation Protocol – used to connect Voice over IP (Internet Protocol) phone calls.	Call control	Approved
IETF RFC 2833	RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals	Encoding and transport of tones over IP	Transport	Approved
draft-ietf-mmusic-sdp-new-26	Session Description Protocol	Contains "text" as an allowable media type. Intended to replace RFC3261	Call control	Draft, for approval
IETF RFC 2198	Redundancy for RTP payloads	Used in RFC4103 for reliability of text traffic	Transport	Approved
IETF RFC 3840	Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)	Can be useful for preference and capability indication for service invocation	Call control	Approved
IETF RFC 3841	Caller Preferences for the Session Initiation Protocol	Can be useful for preference and capability indication for service invocation	Call control	Approved
draft-ietf-avt-rfc2833bisdata	Definition of Events For Modem, FAX, and Text Telephony Signals	Text telephone signals expanded, will replace RFC2833	Transport	Approved by Working group, publication requested
IETF RFC 4504	SIP Telephony Device Requirements and Configuration	Text requirements included, referring to RFC 4103	Device requirements	Approved
IETF RFC 3550	RTP; Real Time Protocol	Media protocol in SIP and others	Transport	Approved
IETF RFC 3711	SRTP; Secure Real Time Protocol	Encryption etc on RTP	Transport	Approved
draft-ietf-ecrit-requirements-09.txt	Requirements for Emergency Context Resolution with Internet Technologies	Requirements for emergency services in IP, including real time teext	Service requirements	Draft

ITU Accessibility specific documents

Document	Title	Explanation	Type	Status
ITU-T Rec. V.18	Operational and Interworking Requirements for DCE:s Operating in the Text Telephone Mode	Includes automatic interworking with most legacy text telephones.	Modem transport	Approved
ITU-T Study Group 16 V.151	Text Telephony over IP	Text Telephony transit through IP.	Gateway	Approved
ITU-T Rec. F.703	Multimedia conversational services	Defines Text Telephony and Total Conversation services	Service description	Approved
ITU-T Rec. H.224	A real time control protocol for simplex applications using the H.221 LSD/HSD/HLP channel.	Addition of client id=2 for T.140 text transport	Transport	Approved
ITU-T Rec. H.323 Annex G	Text Conversation and Text SET.	Defines T.140 text inclusion in H.323 IP Multimedia	Call control	Approved
ITU-T Rec H.323 Annex G v2	Text Conversation and Text SET.	Defines T.140 text inclusion in H.323 IP Multimedia	Call control	Approved
ITU-T Rec.T.134	Text Chat Application Entity	Application for text conversation in the T.120 data conferencing concept.	Transport	Approved
ITU-T Rec. T.140	Protocol for multimedia application text conversation.	Text conversation protocol for multimedia application. With amendment 1 (2000).	Presentation level	Approved
ITU-T Rec.T.140 - Addendum	Marking of missing characters	Replacement for characters missing after transmission	Presentation	Approved
ITU-T H Series Supplement 1	Video Quality for sign language and lip reading	Quality characteristics of video transmission of importance for sign language and lip-reading use.	Requirement	Approved
ITU-T Rec. H.248.2v2	Packages for fax, text and call discrimination	Text telephony to text over IP gateway. Approved revision.	Gateway	Approved

ITU general documents of accessibility interest

*Standard*	*Full Name of Standard*	*Explanation*	*Type*	*Status*
ITU-T Recommendation H.248	Gateway control protocol	Control of gateways.	Gateway	Approved
ITU-T Recommendation H.248.21	Controlled multimedia conferences	Includes text	Conference control protocol	Approved
ITU-T Rec. F.700	Framework Recommendation for multimedia services, Annex A.3.	Multimedia Framework, including real time text	Service description	Approved
ITU-T Rec.V.250	Serial asynchronous automatic dialling and control	Contains modem control for V.18	Call control	Approved
ITU-T Recommendation V.8	Procedures for starting sessions of data transmission over the public switched telephone network	Contains call function = text telephony	Call control	Approved
ITU-T Recommendation V.8 bis	Procedures for the identification and selection of common modes of operation between Data Circuit-terminating Equipments (DCEs) and between Data Terminal Equipments (DTEs) over the public switched telephone network	Contains procedures for starting simultaneous voice and text in V.18.	Call control	Approved
ITU-T V.150.1	Modem transit over IP	International Recommendation for transport of Modem over IP	Gateway	Approved
ITU-T Rec.V.152	Procedures for supporting Voice Band Data over IP networks	Usable for text telephony transit through IP networks	Gateway	Approved
ITU-T Rec.H.324	Terminal for low bit-rate multimedia communication	Addition of data channel for T.140 text	Multimedia system	Approved
ITU-T Rec. V.61	Analog simultaneous voice and data (permits Voice carry over with ASCII modems	Possible to use under V.18	Modem transport	Approved
ITU-T Rec.H.320	ISDN visual telephone systems and terminal equipment.	Text conversation added	Multimedia system	Approved
ITU-T Rec. H.245	Control Protocol for Multimedia Communication	Multimedia Control protocol, includes setup of text channels	Call control	Approved
ITU Y.1541	Network performance objectives for IP-based services		Requirement	Approved
NGN Release 1 Scope	Scope for next generation network	Real time text included	Requirements	Draft
NGN Release 1 Requirements	Requirements for next generation networks	Accessibility additions proposed	Requirements	Draft
F.724	IP Videophone service description	Real time text included	Service description	Approved
F.733	Multimedia conference services	Real time text included	Service description	Approved
F.742	Service description and requirements for distance learning services	Real time text included	Service description	Approved

ETSI and 3GPP Accessibility specific documents

ETSI			*Type*	*Status*
ETSI ETR 333	Text Telephony, User Requirements And Recommendations	Describes user needs for text conversation and guidelines for standardisation	Requirement	Approved.
ETSI TR 101 806	Guidelines for Telecommunication Relay Services for text and video	Guidelines for Telecommunication Relay Services for text and video	Requirement	Approved
ETSI TS 122 226 3GPP TS 22.226	Global Text Telephony Service Stage 1	Global Text and Total conversation (GTT) service description	Service	Approved
ETSI TS 123 226 3GPP TS 23.226	Global Text Telephony Architecture Stage 2	GTT Specific description of network architecture for text conversation and especially CTM text telephony	Architecture	Approved
ETSI TS 126 226 3GPP TS 26.226	CTM Modem, General description	Robust and error tolerant modem for text telephony specified for mobile networks.	Modem transport	Approved
ETSI TS 126 235 3GPP TS 26.235	Packet Switched Conversational Multimedia , default codecs	Includes text conversation using T.140 in RTP as RFC 2793.	Profile	Approved
ETSI TS 126 236 3GPP TS 26.236	Packet switched conversational multimedia, transport.	Includes text conversation transport RFC 2793	Profile	Approved
ETSI EG 202 320	Duplex Universal Speech and Text Communication	Guide for text as a mainstream call component	Requirements and implementation framework	Approved

ETSI and 3GPP general documents of accessibility interest

ETSI and 3GPP			*Type*	Status
ETSI TS 122 101 3GPP TS 22.101	Service principles	Brief description of mobile text conversation	Service	Approved
ESI TS 126 110 3GPP TS 26.110	Circuit Switched Multimedia Telephony ( 3G.324 )	Includes text conversation using T.140 in AL1 channel	Multimedia call control	Approved
ETSI TS 124 008 3GPP TS 24.008	Terminal indicators	CTM indicator from terminal is defined here	Call control	Approved
3GPP TS 26.114	IMS Multimedia Telephony codec principles	Real-time text, video and audio are included	Profile and codec details	Draft

EIA/TIA Accessibility specific Documents

*Standard*	*Full Name of Standard*	*Explanation*	Type	Status
TIA/EIA 825a	A Frequency Shift Keyed Modem for use on the Public Switched Telephone Network	The standard for TTY signals, which permitted mainstream industry to design for compatibility with TTY as technologies moved to digital.	Modem transport	Approved
TIA 1001	Standards for text over IP (TIA 1001) transit gateway	U.S. effort to develop standard methods for carrying Baudot over IP networks, using voice band data and gateway approaches.	Gateway	Approved
TIA- 504-A	Telecommunications-Telephone Terminal Equipment-Magnetic Field and Acoustic Gain Requirements for Headset Telephones Intended for Use by the Hard of Hearing		Requirement	Approved
ANSI/TIA-968-A	Telecommunications - Telephone Terminal Equipment - Technical Requirements for Connection of Terminal Equipment to the Telephone Network		Requirement	Approved
TR 45 TSB-121	2.5 mm Audio Interface For Mobile Wireless Handsets - Text Telephones (TTY)	Connector standard for wireless telephones and TTYs	Physical	Approved
C.63/ANSI ANSI C.63.19	American National Standard for Methods of Measurement of Compatibility between Wireless Communication Devices and Hearing Aids	Measurements of wireless telephone emissions and hearing aid immunity, with predicted performance based on measures. (Now in use in an FCC order)	Interference	Approved
TIA IS-823	TTY/TDD Extension to TIA/EIA 136-410 Enhanced Full Rate Speech Codec		Transport	Approved
TIA -IS-840	Minimum Performance Standards for Text Telephone Signal Detector and Text Telephone Signal Regenerator		Requirements	Approved
TIA TSB-121	2.5 mm Audio Interface For Mobile Wireless Handsets - Text Telephones (TTY)		Physical	Approved

EIA/TIA General documents with accessibility interest.

*Standard*	*Full Name of Standard*	*Explanation*	*Type*	*Status*
TIA IS-127-2	Enhanced Variable Rate Codec, Speech Service Option 3 for Wideband Spread Spectrum Digital Systems - Addendum 2		Speech codec	Approved
TIA IS-707-A-2	Data Services Options for Spread Spectrum Systems - Radio Link Protocol Type 3 - Addendum No. 2			Approved
TIA IS-733-1	High Rate Speech Service Option 17 for Wideband Spread Spectrum Communications Systems			Approved
TIA IS-789A	Electrical Specification for the Portable Phone to Vehicle Interface		Physical	Approved
TIA/EIA-688	DTE/DCE Interface For Digital Cellular Equipment		Physical	Approved
T1.209-2003	American National Standard for Operations Administration and Maintenance and Provisioning (OAM&) – Network Tones and Announcements	Provides and industry standard way for network routing messages to be conveyed in TTY in addition to voice.		Approved

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