Archived from groups: comp.dcom.voice-over-ip (
More info?)
Usually, these parameters refer to how you'd like to pass DTMF digits
to the other end of your call. H323 or SIP signaling will negotiate
your choices with the other end to help establish call parameters. The
choices can be set up for what you want to send (outbound) and what you
want to receive (inbound). Choices are generally:
1) In band digits: digits are passed along with the rest of your voice,
using the same VoIP codec as your voice (G.711, G.729, etc.)
2) Out of band digits using special IP pakets that are sent along with
the voice path. These packets use RFC 2833 format, these packets must
have a "payload type" that matches what the other end is listening for.
Cisco often defaults to 101 for this payload type, which uses your
definition to negotiate (again via H323 or SIP) with the other end
during call establishment. These digits are pulled out of the voice
stream and sent only in the RFC 2833 packets.
3) Out of band digits sent via the signaling layer (UII packets).
These have no payload type defined. The digit is removed from the
voice path and signaling messages are sent to tell the other end about
the digits.
In 2 & 3, when the other end receives these special packets that
represent digit value & duration, it will regenerate the proper tone
and duration back to the voice path.
The purpose of this is to guarantee a valid tone detection at the
distant end of the call, since some voice codecs may not be able to do
that properly (other then G.711 it's a gamble).
Hope this helps,
Greg in MA
xer wrote:
> "Miguel Cruz" wrote:
> > I think it would be easier to help you if you provided more information
> > about what you are trying to achieve. Are you trying to set up a certain
> > piece of equiment? If so, what kind?
> >
>
> Hi Miguel
>
> I have two draytek VigorTalk.
> They works also on a peer to peer instance, but i need to know and learn
> more about DTMF paraeters, no manuals on the website about it.
> That's all.
> Thanx in advance.
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