Subject: [AVT] Combining transmission of in-band and out-of-band information (RF C 2833 and RFC 2198)

From: "Wong, David" <[email-masked]>
Date: Tue, 3 Sep 2002 15:59:35 -0400

If an implementation wants to transmit a DTMF digit as both in-band and
out-of-band (so as an encoded audio clip of the digit and as a named event
from RFC 2833), which of the following is/are correct:
 
1. send the in-band and out-of-band in a single packet, using the
header/format defined in RFC 2198
2. send the in-band and out-of-band in separate packets, one right after the
other (so when captured, this would appear almost as two streams--one
consisting of packets of encoded audio, with an interpacket delay of 20ms,
and one of named events, with an interpacket delay of 20ms)
 
My understanding is that both technically are legal, but that the first
method is preferred because it uses less bandwidth.
 
David Wong
Software Engineer
Communications Infrastructure Test Group

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