[asterisk-dev] Advanced Codec Negotiation: Invite without Offer

[Jöran Vinzens]

Hi,

I think both would be possible. Asterisk could send an Invite w/o SDP to
Bob for the SDP challenge. Then Asterisk gets one back on 200OK, this gets
forwarded to Alice and on the Ack w/ SDP you have your SDP for Bob.
Another possibility Asterisk clears this late SDP challenge when sending
the Invite to Bob with SDP and as soon Bob sends the 200OK w/ SDP we could
use this for 200OK towards Alice. The ACK from Alice finally makes it
complete.

I think for a B2B UA or PBX as I see the Asterisk it should clear the late
SDP no matter if Bob or Alice is outside or inside. So the Invite
coming from Asterisk should always contain an SDP.

This is afaik quite a common use case at least in Germany.

BR Jöran



On Tue, Jun 30, 2020 at 6:43 PM George Joseph <gjoseph at digium.com> wrote:

>
>
> On Tue, Jun 30, 2020 at 9:49 AM Dan Jenkins <dan at nimblea.pe> wrote:
>
>> Hi George,
>>
>> Funnily enough I saw this the other day and the client's
>> Kamailio/RTPProxy setup wasn't set up to handle the reinvite scenario
>> afterwards. From what I understand this is becoming more and more common.
>> So in this case it was an initial request to get the dialog going, once
>> everything had been answered, there was a re-invite to get media flowing
>>
>> Dan
>>
>
> Wow.  What should we have done in this case?  If Alice is on the outside
> calling Bob on the inside should we be sending an offer to Bob if we didn't
> get one from Alice?  What do we send back in the initial 200 OK to Alice?
> An offer?  Nothing? ???
>
>
>
>
>>
>> On Tue, Jun 30, 2020 at 4:31 PM George Joseph <gjoseph at digium.com> wrote:
>>
>>> There's a feature we currently support where Alice can send us an INVITE
>>> without an SDP offer.
>>> https://tools.ietf.org/html/rfc6337#section-3.1.2
>>>
>>> How often do you see this and with what scenarios/devices?
>>>
>>>
>>> --
>>> George Joseph
>>> Asterisk Software Developer
>>> direct/fax +1 256 428 6012
>>> Check us out at www.sangoma.com and www.asterisk.org
>>> [image: image.png]
>>> --
>>> _____________________________________________________________________
>>> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
>>>
>>> asterisk-dev mailing list
>>> To UNSUBSCRIBE or update options visit:
>>>    http://lists.digium.com/mailman/listinfo/asterisk-dev
>>
>> --
>> _____________________________________________________________________
>> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
>>
>> asterisk-dev mailing list
>> To UNSUBSCRIBE or update options visit:
>>    http://lists.digium.com/mailman/listinfo/asterisk-dev
>
>
>
> --
> George Joseph
> Asterisk Software Developer
> direct/fax +1 256 428 6012
> Check us out at www.sangoma.com and www.asterisk.org
> [image: image.png]
> --
> _____________________________________________________________________
> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
>
> asterisk-dev mailing list
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-dev



-- 

Jöran Vinzens - vinzens at sipgate.de
Telefon: +49 211-63 55 56-21
Telefax: +49 211-63 55 55-22

sipgate GmbH - Gladbacher Str. 74 - 40219 Düsseldorf
HRB Düsseldorf 39841 - Geschäftsführer: Thilo Salmon, Tim Mois
Steuernummer: 106/5724/7147, Umsatzsteuer-ID: DE219349391

www.sipgate.de - www.sipgate.co.uk
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.digium.com/pipermail/asterisk-dev/attachments/20200630/b6156c95/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 5142 bytes
Desc: not available
URL: <http://lists.digium.com/pipermail/asterisk-dev/attachments/20200630/b6156c95/attachment.png>