[Asterisk-Users] dtmfmode=inband with G.729

[Jim Rosenberg]

On Fri, Apr 02, 2004 at 08:52:09AM -0600, Eric Wieling wrote:
> It's not asterisk, its the codecs.  Codecs other than ulaw and alaw will
> distort continuous tones like DTMF.

Welllllllllll ...

At work we experience this with Cisco dial-peers over G.729: DTMF is
erratic. But it's *NOT* inoperable. The way Asterisk does this, it
doesn't even *try* to send the data through. I'd sure like that option,
even if it might not register at the other end.

My Cisco-dial-peer-only connection users tell me that they often have to
try a second time, but DTMF does usually work for them eventually.

"Might not resgister" does beat "Refuse to try" ...

If you have an actual IVR application where errors matter, then of
course you might decide you wouldn't want the risk of distored DTMF, but for
simple things like picking an extension on a PBX where the consequence
of an error is just a wrong number, why not give it a go?

Anyone who chooses dtmfmode=inband is knowingly choosing an option that
is inherently error-prone.