1 TR41.4/ VON_Text_Telephony_GH2

2 Text Telephony and Total Conversation in the IP revolution Gunnar Hellström, Omnitor AB

3 Accessibility opportunities in IP networks IP networks take over telecomm traffic Opportunity: –Combine text, video and voice –Interworking between many ways to access the network –Next generation mobile will have IP capabilities Important points to consider –Interworking with Textphones in the Telephone Network is desired. –IP Transit for textphones requires special consideration –A simple IP textphone is needed

4 Total Conversation standards Text conversation need standards as well as video and audio. Work is close to completion in ITU-T and IETF to define extension of video telephony to Total Conversation with video, text and voice Subsets are possible for text telephony

5 Example of a Total Conversation Terminal Voice Text in video call Sign language Text telephony

6 Opportunities with Total Conversation Deaf: sign, type or lip-read as the situation calls for. Adult deaf: speak and see and get text back. Hearing impaired – Hear and lip-read as far as possible, revert to text when needed. Video relay services: Transfer phone number to call Speech impaired: Hear and type. Or hear and speak and revert to typing when needed. Anyone: Communicate in preferred mode, type when needed for names, phone numbers etc.

7 Further opportunities with local additions to Total Conversation Screen reader and Braille display makes text conversation accessible to deaf-blind users. Voice recognition can make voice conversation convenient with adult deaf users.

8 T.140, the common base for text conversation Standardised in ITU-T 1998 Extremely simple end-to-end text chat protocol User input to Unicode UTF-8 coded transmission UTF-8 transmission to display Safe and easy to include everywhere What is the street address? Alameda 34 User T.140 Channel

T.140 text protocol Character by character transmission Character code for any language: ISO (= Unicode). Control from ISO 6429: –Erase last character, –New line, –Nelect graphic rendition –Alert in session Transport channel must be specified for each environment. T.140 Channel User application Network

10 Text Telephony, a subset of Total Conversation IP Telephony builds on IP Multimedia technology. IP Text Telephony builds on IP Total Conversation technology –ITU-T H.323 Annex G Text Conversation and Text SET. IP telephone extension with text –IETF RFC 2793 transport for text in IP networks –Usable in IETF multimedia protocol SIP

Text in IP networks H.323 Annex G = text in the dominating IP telephony protocol H.323 SIP text conversation also possible without further specfikation IP Textphone or Total Conversation terminal IP textphone T.140 Text RTP T.140 Text RTP Text in IP networks Audio RTP Audio (and Video) RTP IP Network

12 Total Conversation - a complete family V.18 Texttelephony Trans parent Equal - izers T.140 PSTN H.223 V.34/V.80 AL1 H.245 H. 324 T. 140 Voice and video PSTN H.221 Network access H. 320 H.224 T. 140 Voice and video ISDN H.323 Network access T.140 Voice and video IP H.324 Mobile system H.223 Mobile transmission Voice and video AL1 H.245 T.140 MOBILE T.124 GCC T.134 T.120 Data conferencing T.123 T.140 H.248 Annex F. Text - aware Gateway For decision in ITU 13 Nov Ready RTP DATA TCP/RTP

13 V.18 An automoding modem - a bridge to mono media text Can be used in gateways and servers USA, UK USA Holland Germany France Anywhere Sweden, UK Example of use

Text telephone interworking T.140 is also used in standardised text telephony. V.18 enables communication with a huge number of existing text telephones T.140 equalizers for legacy modes T.140 ready transmission in V.18 mode T.140 V.18 text telephone modem

15 PSTN Interworking Gateways need to have V.18 capabilities, to connect PSTN text telephone calls with Total Conversation or IP Text Telephone terminals Gateways need to be T.140 aware PSTN Textphone Gateway H.323 Annex G T.140 text in IP channel RTP/Audio Gateway example V.18 - H.323 V.18 compa- tible text V.18 /T. 140 T.140 alternating with voice

16 Textphone gateway call between Telephone network and IP network

17 Textphone call in telephone network passing through IP network

18 IP gateway standardisation ITU-T H.248 and IETF Megaco Current hot topic – huge efforts. Text telephone and text conversation additions. Integration of text – fax – modem additions Possible use – same port for voice, text, fax and modem, automatic identification of mode and invocation of proper packetization.

Conclusions Video telephony is complemented with text to form Total Conversation Text Telephony is linked in through a standardised bridge – V.18 Work is centered in ITU-T SG 16 with Q9-Accessibility as initiator Many companies and organisation have contributed Standards are in place, implementations emerge

20 Standards support for Total Conversation and text telephony F.MCVS Service Description Text telephony (PSTN) V.18 Text, video and voice ISDN- H.320 H.224 Text, video and voice (IP) H.323 Annex G RTP-Text Text, video and voice (PSTN) H.324 Mobile text H.324M Gateway H.248 Text conversation T.140 Data conferencing T.120, T.134