6. ICT with two way voice communication
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Where ICT provides two-way voice communication, in order to provide good audio quality, that ICT should be able to encode and decode two-way voice communication with a frequency range with an upper limit of at least 7 000 Hz.
6.2.1. RTT provision
Where ICT supports two-way voice communication in a specified context of use, the ICT shall allow a user to communicate with another user by RTT.
Where the ICT, or set of ICT, provided to a user, supports two-way voice communication and enables a user to communicate with another user by RTT, it shall provide a mechanism to select a mode of operation allowing concurrent voice and text.
6.2.2. Display of Real-time Text
Where ICT has RTT send and receive capabilities, displayed sent text shall be visually differentiated from and separated from received text.
Where ICT has RTT send and receive capabilities, the send/receive direction of transmitted text shall be programmatically determinable, unless the RTT has closed functionality.
6.2.3. Interoperability
Where ICT with RTT functionality interoperates with other ICT with RTT functionality (as required by 6.2.1.1) they shall support at least one of the four RTT interoperability mechanisms described below:
a) ICT interoperating over the Public Switched Telephone Network (PSTN), with other ICT that directly connects to the PSTN as described in Recommendation ITU-T V.18 [i.23] or any of its annexes for text telephony signals at the PSTN interface;
b) ICT interoperating with other ICT using VOIP with Session Initiation Protocol (SIP) and using real-time text that conforms to RFC 4103 [i.13];
c) ICT interoperating with other ICT using RTT that conforms with the IP Multimedia Sub-System (IMS) set of protocols specified in TS 126 114 [i.10], TS 122 173 [i.11] and TS 134 229 [i.12];
d) ICT interoperating with other ICT using a relevant and applicable common specification for RTT exchange that is published and available. This common specification shall include a method for indicating loss or corruption of characters.
6.2.4. Real-time text responsiveness
Where ICT utilises RTT input, that RTT input shall be transmitted to the ICT network supporting RTT within 1 second of the input entry.
Where ICT provides caller identification and similar telecommunications functions are provided, the caller identification and similar telecommunications functions shall be available in text form and in at least one other modality.
Where ICT provides real-time voice-based communication and also provides voice mail, auto-attendant, or interactive voice response facilities, the ICT should offer users a means to access the information and carry out the tasks provided by the ICT without the use of hearing or speech.
6.5.1. General (informative)
Clause 6.5 (Video communications) provides performance requirements that support users who communicate using sign language and lip-reading. For these users, good usability is achieved with Common Intermediate Format (CIF) resolution, a frame rate of 20 frames per second and over, with a time difference between speech audio and video that does not exceed 100 ms.
6.5.2. Resolution
Where ICT that provides two-way voice communication includes real time video functionality, the ICT:
a) shall support at least QCIF resolution;
b) should preferably support at least CIF resolution.
6.5.3. Frame rate
Where ICT that provides two-way voice communication includes real-time video functionality, the ICT:
a) shall support a frame rate of at least 12 frames per second (FPS);
b) should preferably support a frame rate of at least 20 frames per second (FPS) with or without sign language in the video stream.
6.5.4. Synchronization between audio and video
Where ICT that provides two-way voice communication includes real-time video functionality, the ICT should ensure a maximum time difference of 100 ms between the speech and video presented to the user.
Where ICT provides real-time video-based communication and also provides answering machine, auto attendant or interactive response facilities, the ICT should offer users a means to access the information and carry out the tasks related to these facilities:
a) for audible information, without the use of hearing;
b) for spoken commands, without the use of speech;
c) for visual information, without the use of vision.