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.


  1. Input entry is considered to have occurred when sufficient user input has occurred for the ICT to establish which character(s) to send.
  2. Input entry will differ between systems where text is entered on a word-by-word basis (e.g. speech-to-text and predictive-text based systems) and systems where each character is separately generated.

Testing methods

Type of complianceInspection of Measurement data or Test
  1. The ICT under test has RTT send and receive capabilities.
  2. A "reference" RTT-capable terminal using mechanisms supported by the ICT network is connected at the other end of an ICT network to the terminal under test.
  3. The ICT under test is connected to the ICT network terminated by the "reference" terminal.
  4. The different elements of the ICT are in a working status (the connection is active and the terminals are in the relevant RTT mode).
  1. A short sequence is input to the terminal under test.
  2. Check the time at which input entry has occurred.
  3. Check the period between input entry to the ICT terminal under test and the time when the text is transmitted to the ICT network.
Result  Pass: Check 3 is less than or equal to 1 second
 Fail: Check 3 is greater than 1 second
NOTE:   As described in the notes to clause 6.3.4, the identification of when input entry has occurred may vary according to the type of RTT system under test.

Requirement details

Reference number: 6.2.4

Related requirements

Related functional statements

Related technical requirements

No related technical requirements are associated with this technical requirement