ETSI - PRETS 300 834
Terminal Equipment (TE); Narrowband Networks (PSTN or ISDN); Access to Interactive Audio-Visual Retrieval Services without Data-Facility; Access for ISDN or PSTN Videophony Terminals to Audio-Visual Databases
|Publication Date:||1 January 1998|
This European Telecommunication Standard (ETS) specifies how narrowband (Integrated Services Digital Network (ISDN) or Public Switched Telephony Network (PSTN)) videophony terminals without data-facility can access interactive audio-visual retrieval services. To control the retrieval process, the terminal should support some interactive protocol between the end user and the service centre. For ISDN videophony terminals, the solutions using inband signalling via Dual Tone Multi Frequency (DTMF), CCITT Recommendation Q.23  in the audio stream and the use of transmitting Single Byte Extension (SBE) control and indication messages (ETS 300 144 ) are specified in this ETS. In the case of the PSTN, use of transmitting UserInputIndication (UII) via ITU-T Recommendation H.245  messages in the control channel is specified. In I-ETS 300 837 , this user input is not considered as data capability.
The use of DTMF, SBE and UII enables a user to control the retrieval process via input of alphanumeric characters from a keypad or keyboard, equivalent to the DTMF signals used in analogue telephony. This may be used to manually operate remote equipment such as voice mail or video mail systems, menudriven information services etc. DTMF, SBE and UII support at least, the transmission of user input characters '0-9', '*', and '#'. Transmission of other characters is optional. The use of DTMF, SBE or UII as interactive protocols is very simple, since the service centre can instruct the user, either in text or spoken, in the same way as in voice response systems.
For Personal Computer (PC) / Work station (WS) based ISDN and PSTN videophony terminals, an additional selection mechanism that permits pointing device selections via (push) buttons in the video presentation area using SBE or UII messages is specified.
This ETS is applicable to audio-visual services based on retrieval of information, coded according to ETS 300 145  (in the ISDN case) or I-ETS 300 837  (in the PSTN case). In this ETS the definition "videophony" is used to address both videotelephony and videoconferencing applications.
The audio-visual retrieval services will be hosted on an audio-visual service centre. In this ETS only the audio-visual database functionality of the service centre will be specified.
NOTE: Information retrieval using videophony terminals in combination with DTMF or SBE/UII, are only two of the possible scenarios for the access of retrieval services and audiovisual services on narrowband networks. In ETR 176 and ETR 272 (see annex A) other scenarios have been described.