UserInputSupportedIndication (Q116)

The information in this article applies to:

The userInputSupportIndication codepoint is restrictive, not merely advisory. For example, upon receipt of the CHOICE, UserInputIndication.userInputSupportIndication.basicString, a UserInputIndication (UII) transmitter must only send 0-9, * and #.

This codepoint does not mean that transmitters must send these but can also send others because that would be redundant with 6.2.8/H.323v2: "H.323 terminals shall support the transmission of user input characters 0-9, '*', and '#'. Transmission of other characters is optional."

Here's a little background. UserInputSupportIndication came about because it was generally conceded early on but too late to modify H.245v1 that it was a mistake to have specified GeneralString for UII because the character set was way too large and would have imposed an unreasonable burden on receivers when we mostly just wanted to convey a rather small character set.

UserInputSupportIndication was added to H.245v2; whereas UserInputCapability was added to H.245v3. The latter is now the prefered means of indicating what type of UII one supports, but receipt of the former must also be supported for backward compatibility.