Andreas,
My thouhts are if you include the a=fmtp line in the SDP as you
have illustrated below then the receiver knows you are capable of
recieving those DTMF and Tone events - but if the Answerer does not return
the a=fmtp SDP line in the response with it's supported events then the
Offerer will not be able to assume to use them. Comments inline -
>To show what kind of events values (RFC2833 DTMF) a UA can receive it
"may"
>send a attribute a=fmtp:101 0-15,66,70.
>As I understand, if a AU receives this information from the remote side
in
>an invite, this UA doesn't have to add a fmtp in the 200 OK if it only
can
>receive 0-15 (since this is mandatory)? Is this a valid scenario:
>>From A in invite:
>a=fmtp:101 0-15,66,70
>>From B in 200 OK:
>No fmtp attribute.
Wayne - I am thinking in this scenario B would be able to send the 0-15
DTMF events and 66, 70 Tone events to A but A should not send them to B as
B has not advertised support for it ?. If B is prepared to accept those or
a subset it should include it in the response.
>In the call above, A and B will send dtmf using rfc2833 for 1-15?
>If AU initiate a call and wants to use rfc2833 dtmf for format 1-15, it
>should be enough to have:
>m=audio 7000 RTP/AVP 0 8 101
>a=rtpmap:0 PCMU/8000
>a=rtpmap:8 PCMA/8000
>a=rtpmap:101 telephone-event/8000
>Sending this media description above will indicate for the remote side
that
>I want to use out of band dtmf according to rfc2833 and I can receive
dtmf
>events 0 to 15? This means it is no need for me to add fmtp if I only
>support events 1-15?
Wayne - yes, the above is my understanding as well.
>Regards,
>// Andreas
Regards, Wayne
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