[Asterisk-Users] Problem with Aterisk 1.2.0 beta 2 and sip dtmf

Mike Bernson mike at mlb.org
Sun Nov 6 17:30:01 MST 2005


I have a number of sipura 2002 ATA connected to asterisk.

I have set them up with 'dtmfmode=rfc2833' for handling dtmf.

I then setup setup an extension  to test sending
dtmf tones.
exten => *40,1,Answer
exten => *40,n,Wait(2)
exten => *40,n,SendDTMF(123456789,500)
exten => *40,n,Hangup

When a Call the extension I get a bunch of very short clicks but not
the valid dtmf tones.

I then use ethereal to look at what is being set I got the following

3 packets RFC2833 DTMF event packet that where the same bu the
sequence number increrment by 1.
timestamp 0
Sequence number incrment by 1 for each
end event  0
volume       10
duration    0

followed by 3 RFC2833 DTMF event packet that were the same.
Timestamp 0
Sequence number same for all 3
end event 1
volume      10
duration    800

This does not look at all correct to me.


Should it have sent
TimeStamp 0
Sequence Number
end Event 1
volume      10
duration   800

or
TimeStamp 0
Sequence Number
end Event 0
volume      10
duration    x
then
Timestamp  x
sequece Number +1
end Event   1
volume         10
duration      (number of count left)


Now a couple of question about the 3 events

Why does asterisk send 3 RFC2833 events with the same timestamp for 1 
start of tone ?

Why is the duration set to zero at the start (is the min value for
duration 40 ms not zero) ?

Why does asterisk send end event with the same timecode as the
start event ?

Is there a reason not to send 1 DTMF event with the end bit sent
and the duration correct ?

As a note this play ok on SIPURA 841 but not 3k or 2002.





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