I am trying to find an answer to the following question - neither
AT&T's Q.931 spec nor an ANSI draft I have give any helpful
How do you do keypad terminal to terminal signalling in ISDN? In other
words, what happens when you press a key on a voice-only ISDN phone
during an active call?
If you have one of the few ISDN lines Illinois Bell has installed, and
you dial an 800 number on the public network, what happens when you hear
"press 1 if you have a touch-tone phone"? If you can use this service,
where is the DTMF tone produced? The terminal? The local switch or
the interworking point? If so, what Q.931 message conveys the keypad
information? Will this message be carried end-to-end within an ISDN to
allow the same signalling without generating DTMF?
[if you post, please e-mail to remind me to read it.]
enquiring minds want to know...