[Asterisk-Dev] Re: DTMF when transferring calls - not handled well?

[Bryan Field-Elliot]

On Mon, 2005-05-23 at 17:04 -0400, Dan Evans wrote:

> Asterisk has always "normalized" RFC2833 DTMF input.  Initially, it sent 
> 1 "DOWN" ("ON") followed by 3 "UP"s ("OFF").  I believe the 3 
> terminating packets are recommended in the RFC.  But having only 1 DOWN 
> meant that your DTMF would disappear if that one packet was dropped. 
> The UP's would just look like events associated with the previous keystroke.
> 
> The normaization was changed to 3 DOWN and 3 UP in patch 0003339 (sic), 
> to improve robustness.


Thanks Dan, 

I understand now why Asterisk is sending it three times (it really is
redundancy), and I presume that most SIP ATA's are expected to handle
the redundant packets correctly. My issue is that I have 3 ATA's from 3
different manufacturers, not re-creating the digit audio correctly, so I
am wondering if there is some flaw in how Asterisk is creating these
packets. I'll be doing more testing tonight.
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