H.245 User Input Indication question

Dave Lindbergh lindbergh at 92f1.com
Tue Mar 16 11:48:31 EST 2004

Hi Paul,

My recollection is that "are supported" was meant to indicate that the 
device can send those characters.  (I think UII can send anything in the 
ASCII, and perhaps the Unicode, set.)

The purpose of the "are supported" bit is to allow an automatic menu 
generator to limit the kinds of input it requests to what the far-end 
terminal can actually send.  (weak example: "Press # for Customer Service" 
vs "Type SERVICE for Customer Service")...in fact people have used UII to 
do things like text chat, which is difficult with only a phone keypad.


At 11:40 AM 3/16/2004, Paul E. Jones wrote:
>I have a question regarding H.245 User Input Indication.  In section 
>B.14.6, it states:
>     "The boolean basicString, when true, indicates that the characters 
> 0-9, * and # are supported."

>My question is whether that those characters are supported means that it 
>is the only valid characters that may be transmitted?  Or is it also valid 
>to transmit A,B,C,D, for example?  In other words, does this wording 
>simply indicate the minimum set of characters that must be supported or is 
>the wording intended to specify the complete set of characters that may be 
>used with "basicString".
>H.323 Section 6.2.8 simply says that "alphaNumeric" must be supported and 
>that the characters 0-9, * and # must be supported and others are 
>optional.  However, it does not speak to whether endpoints must advertise 
>support for basicString, IA5String, etc.
>A second question: can somebody explain why there is a CHOICE of 
>"userInputSupportIndication" inside the UserInputIndication 
>message?  Would we not always advertise capabilities via the 
>UserInputCapability only?  Is the intent of having the 
>"userInputSupportIndication" for changing capabilities outside of a normal 
>capability exchange.
>Any clarification you can provide would be most appreciated.

Dave Lindbergh
Polycom, Inc.
100 Minuteman Road
Andover MA 01810  USA
Voice: +1 978 292 5366
Email: lindbergh at 92F1.com
H.320, H.323 video by arrangement
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