Re: [MMUSIC] Offer/Answer PT Questions

[Roman Shpount <[e-mail]>]

On Wed, Feb 24, 2016 at 12:15 PM, Dale R. Worley <[e-mail]> wrote:

> Roman Shpount <[e-mail]> writes:
> > 2. Is PT blocked from each direction independently or both directions at
> > the same time. For instance if A sent an offer with PT=100, but B never
> > sent an offer or an answer with PT=100, can B sent an offer with PT=100?
>
> My understanding is that the answer to 2 has always been understood to
> be that the PT number spaces in each direction are independent.  For
> instance, RFC 3264 section 5.1 notes
>
>       Different payload type numbers may be needed in each direction
>       because of interoperability concerns with H.323.
>
>
Based on this, the answer to original question is that if

1.Alice sends an Offer, with the following PT values:

PT 100: AMR-WB(mode-set=2)
PT 111: AMR-WB(mode-set=2, OA)
PT 0: PCMU

2.Bob sends the associated Answer:

PT 100: AMR-WB (mode-set=2)
PT 0: PCMU

3.Later Bob sends the following subsequent Offer:
PT 111: AMR(mode-set=0,2,5,7)

This offer should be accepted. PT is each direction is independent and Bob
is allowed to reuse it.

The complication here is that Alice will not be allowed to reuse PT 111
for AMR(mode-set=0,2,5,7) in the answer. Alice will need to pick a
different PT for AMR(mode-set=0,2,5,7), if it is supported and end points
will use asymmetric payload types.

_____________
Roman Shpount