[asterisk-biz] Solving DTMF issue

[Trixter aka Bret McDanel]

On Wed, 2008-04-02 at 20:15 -0400, Gregory Boehnlein wrote:
> > > This was only true with Asterisk up to and including 1.2; 1.4 and
> > beyond
> > > send proper RFC2833 (now RFC4833) DTMF telephone-events and
> > > interoperability has been dramatically improved.
> > 
> > my patch was for 1.4 so that is not true.
> 
> What specifically does the 1.4 DTMF implementation break in terms of the
> RFC? RFC-2833 is pretty vague about a lot of things, and most vendors
> implementations (Cisco, Avaya, Sonus etc..) can be deemed to be "in
> violation" of the RFC. For example Cisco doesn't respect DTMF duration
> events, and clips DTMF upon receipt of a DTMF "end of event" marker.
> Technically this violates the RFC.
> 
duration per the rfc is optional, recommended for pstn gateways, but
optional.

But aside from that there are issues, some of them such as the one I
will say here (only becuase its been a couple months and I dont recall
everything that I did, although it was all very obvious stuff if you
look at it with a packet sniffer such as wireshark).  RTP timestamps
dont match, they are just plain wrong infact (1.4.15 was what I did this
in, yes rtp is rfc1889 but this is in the 2833 generation code and only
happens when it generates a 2833 packet, so its clumped together with
the other things I fixed).

At the time I gave oej a full list via irc, he made some comment on the
bug issue and I kinda left it alone.  I think there were 3-4 things
fixed, this is either 25% or 33% of it, I just dont recall right now.

> In a lot of ways, the Asterisk RFC-2833 implementation is more compatible
> (in 1.4) than most other stacks out there.

That may be, however it doesnt mean that its compliant :)  
-- 
Trixter http://www.0xdecafbad.com     Bret McDanel
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