Hi Sundbaum
There is a codec mismatch between A and B - either of them have to change
or a transcoder needs to be used

Regards
Ranjit

On Fri, Jan 22, 2021 at 11:34 AM Sundbaum Per-Johan (Telenor Sverige AB) <
per-johan.sundb...@telenor.se> wrote:

> Hi !
>
> My tool is exporting the trace as requested, but it seems the resulting
> .pcap is not decoded so that one is not to any use.
>
> I have attached a HTML-version that I hope is at least a little better
> than my text.
>
>
>
>
>
> BR/pj
>
>
>
> *From:* Ranjit Avasarala <ranjitka...@gmail.com>
> *Sent:* den 22 januari 2021 18:02
> *To:* Sundbaum Per-Johan (Telenor Sverige AB) <
> per-johan.sundb...@telenor.se>
> *Subject:* Re: [Sip-implementors] reuse of payload type
>
>
>
> Hi Sundhaum
>
>
>
> either A or B should change in order to make a successful call or make use
> of codec conversion.  instead of pasting the call flows, it will be better
> if u could attach the pcap file.
>
>
>
> On Fri, Jan 22, 2021 at 10:02 AM Sundbaum Per-Johan (Telenor Sverige AB) <
> per-johan.sundb...@telenor.se> wrote:
>
> Much appreciated, thanks !
>
> I have added some more info.
>
>
>
> pCSCF --------- VoLTE-phone
>
> INVITE ->
>
> With SDP offer
>
>              <- 180 Ringing
>
>              <- 200OK with SDP answer
>
> ACK ->
>
> re-INVITE ->
>
> without SDP
>
>              <- 200OK with SDP Offer
>
> ACK ->
>
> With SDP answer
>
>
>
>
>
> SDP in initial INVITE
> SDP PDU
>          v=0
>          o=- 805658488335263 1704590316 IN IP6 2A02:1400:10:1C::4
>          s=-
>          c=IN IP6 2a02:1400:10:1::4
>          t=0 0
>          m=audio 5394 RTP/AVP 108 102 8 100 96 0 116 111
>          b=AS:141
>          a=rtpmap:108 AMR/8000
>          a=fmtp:108 mode-set=7; mode-change-period=2;
> mode-change-capability=2; mode-change-neighbor=1; max-red=0
>          a=rtpmap:102 AMR/8000
>          a=fmtp:102 mode-set=7; max-red=0
>          a=rtpmap:8 PCMA/8000
>          a=rtpmap:100 AMR/8000
>          a=fmtp:100 mode-change-period=2; mode-change-capability=2;
> mode-change-neighbor=1; max-red=0
>          a=rtpmap:96 AMR/8000
>          a=fmtp:96 max-red=0
>          a=rtpmap:0 PCMU/8000
>          a=rtpmap:116 telephone-event/8000
>          a=ptime:20
>          a=maxptime:20
>          a=rtpmap:111 telephone-event/16000
>
> SDP in 200OK from VoLTE-phone with SDP as answer on initial INVITE
>          o=sip:+46708xxx...@ims.mnc008.mcc240.3gppnetwork.org 1611316978
> 0 IN IP6 2a02:1400:df:245d:435:1205:68e0:1ac3
>         s=-
>         c=IN IP6 2a02:1400:df:245d:435:1205:68e0:1ac3
>         t=0 0
>         a=sendrecv
>         m=audio 49120 RTP/AVP 108 116
>         b=AS:37
>         b=RS:462
>         b=RR:1387
>         a=rtpmap:108 AMR/8000
>         a=fmtp:108 mode-set=7; max-red=0; mode-change-capability=2;
> mode-change-period=2; mode-change-neighbor=1
>         a=rtpmap:116 telephone-event/8000
>         a=fmtp:116 0-15
>         a=ptime:20
>         a=maxptime:20
>         a=sendrecv
>
>
> SDP in 200OK from VoLTE-phone with SDP offer as answer on INVITE without
> SDP
>       SDP PDU
>          v=0
>          o=sip:+46708xxxx...@ims.mnc008.mcc240.3gppnetwork.org 1611316978
> 1 IN IP6 2a02:1400:df:245d:435:1205:68e0:1ac3
>          s=-
>          c=IN IP6 2a02:1400:df:245d:435:1205:68e0:1ac3
>          t=0 0
>          a=sendrecv
>          m=audio 49120 RTP/AVP 109 104 110 102 108 105 100
>          b=AS:50
>          b=RS:625
>          b=RR:1875
>          a=rtpmap:109 EVS/16000
>          a=fmtp:109 br=13.2-24.4; bw=nb-wb; max-red=0; cmr=-1;
> ch-aw-recv=-1
>          a=rtpmap:104 AMR-WB/16000
>          a=fmtp:104 max-red=220; mode-change-capability=2
>          a=rtpmap:110 AMR-WB/16000
>          a=fmtp:110 octet-align=1; max-red=220; mode-change-capability=2
>          a=rtpmap:102 AMR/8000
>          a=fmtp:102 max-red=220; mode-change-capability=2
>          a=rtpmap:108 AMR/8000
>          a=fmtp:108 octet-align=1; max-red=220; mode-change-capability=2
>          a=rtpmap:105 telephone-event/16000
>          a=fmtp:105 0-15
>          a=rtpmap:100 telephone-event/8000
>          a=fmtp:100 0-15
>          a=ptime:20
>          a=maxptime:20
>          a=sendrecv
>
>
> ACK with SDP as answer on offer from VoLTE-phone
>
>       SDP PDU
>
>          v=0
>
>          o=- 805658488335263 1704590317 IN IP6 2A02:1400:10:1C::4
>
>          s=-
>
>          c=IN IP6 2a02:1400:10:1::4
>
>          t=0 0
>
>          m=audio 5394 RTP/AVP 104 105
>
>          b=AS:54
>
>          a=rtpmap:104 AMR-WB/16000
>
>          a=fmtp:104 mode-set=0,1,2; mode-change-period=2;
> mode-change-capability=2; mode-change-neighbor=1; max-red=0
>
>          a=rtpmap:105 telephone-event/16000
>
>          a=ptime:20
>
>          a=maxptime:40
>
> BR/pj
>
>
>
>
>
>
>
> -----Original Message-----
> From: Paul Kyzivat <pkyzi...@alum.mit.edu>
> Sent: den 22 januari 2021 16:31
> To: Sundbaum Per-Johan (Telenor Sverige AB) <per-johan.sundb...@telenor.se>;
> sip-implementors@lists.cs.columbia.edu
> Subject: Re: [Sip-implementors] reuse of payload type
>
>
>
> On 1/22/21 7:55 AM, Sundbaum Per-Johan (Telenor Sverige AB) wrote:
>
>
>
> [snip]
>
>
>
> > As you can see the offer in initial INVITE have payload type 100:
>
> > a=rtpmap:100 AMR/8000 The offer in 200OK also have payload-type 100,
>
> > but now it is: a=rtpmap:100 telephone-event/8000
>
> >
>
> > I believe that this is causing failure when B-side (VoLTE-phone) is
>
> > sending TelephoneEvent(DTMF) to A-side (UAC)
>
> >
>
> > Do you think A-side should adapt or maybe reject the offer in 200OK or
> do something else ?
>
> >
>
> >
>
> > RFC3264  8.3.2
>
> >     "However, in the case of RTP, the mapping from a particular dynamic
> payload type
>
> >     number to a particular codec within that media stream MUST NOT change
>
> >     for the duration of a session.  For example, if A generates an offer
>
> >     with G.711 assigned to dynamic payload type number 46, payload type
>
> >     number 46 MUST refer to G.711 from that point forward in any offers
>
> >     or answers for that media stream within the session. "
>
>
>
> I compared the two SDPs and find that there aren't *any* codec+fmtp sets
> that match. So this is messed up. But you haven't provided enough
> information to fully decipher what is going on. We need to see the answer
> to the first invite. The restrictions of rfc3264 section 8.3.2 pertain to
> the PT values used by a particular endpoint. (It is permissible to use
> different PTs on the two ends.) But in this case there isn't anything that
> could be in that first answer that could render this second answer valid.
>
>
>
> Regarding whether the A-side should adapt or reject: this is an
> implementation decision. The specs don't specify behavior for
> non-conforming usage. Or course there is also the problem that you can't
> reject an answer. All you can do is try sending another offer, or else
> terminate the call.
>
>
>
> It isn't entirely clear what you could try in order to carry on while
> accepting this 2nd answer. You could start sending using one or more of the
> codecs in the answer, but it is unclear what you would expect to receive.
>
>
>
>                              Thanks,
>
>                              Paul
>
>
>
>
> Sensitivity: Internal
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>
>
> Sensitivity: Internal
>
>
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