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Re: Teleco Integrators vs Web Developers vs Browser Implementers

From: Christer Holmberg <christer.holmberg@ericsson.com>
Date: Wed, 3 Jul 2013 11:41:02 +0000
To: Eric Rescorla <ekr@rtfm.com>
CC: piranna_gmail.com <piranna@gmail.com>, Robin Raymond <robin@hookflash.com>, Ted Hardie <ted.ietf@gmail.com>, cowwoc <cowwoc@bbs.darktech.org>, Roman Shpount <roman@telurix.com>, Adam Bergkvist <adam.bergkvist@ericsson.com>, public-webrtc_w3.org <public-webrtc@w3.org>
Message-ID: <7594FB04B1934943A5C02806D1A2204B1C3C2059@ESESSMB209.ericsson.se>
Hi,

I agree that the intention of PRANSWER was to support SIP forking etc - and initially I even supported the idea :)

But, as I started to look deeper into it, drawing flows etc, I realized there are problems.

Regards,

Christer



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-----Original Message-----
From: Eric Rescorla [ekr@rtfm.com]
To: Christer Holmberg [christer.holmberg@ericsson.com]
CC: piranna@gmail.com [piranna@gmail.com]; Robin Raymond [robin@hookflash.com]; Ted Hardie [ted.ietf@gmail.com]; cowwoc [cowwoc@bbs.darktech.org]; Roman Shpount [roman@telurix.com]; Adam Bergkvist [adam.bergkvist@ericsson.com]; public-webrtc@w3.org [public-webrtc@w3.org]
Subject: Re: Teleco Integrators vs Web Developers vs Browser Implementers



On Tue, Jul 2, 2013 at 11:38 AM, Christer Holmberg <christer.holmberg@ericsson.com<mailto:christer.holmberg@ericsson.com>> wrote:
Hi,

I am not going to jump into the SDP O/A discussion, but just to comment on PRANSWER.

>> It has been said always that SDP was choosed so WebRTC would be compatible with current VoIP devices and software, so you could
>> make calls from your browser without needing a proxy. Problem is, that WebRTC has evolve a lot adding a lot of features (panswer SDP message,
>
> Huh? PRANSWER is specifically designed to enable/model existing
> SIP/SDP features, namely serial forking and 180.

PRANSWER tries to map multiple early SIP legs (in the case of forking) into a single "leg", but it does not work, at least not as currently defined, because it prevents the sending and receiving of additional offers while in the pranswer state.

People have said "Well, just don't use PRANSWER, and it works.". Well, while that is true, then the whole forking support goes away.

I have tried to explain this to some people (including Ekr) off-line in the past, but obviously I haven't done a good job, so I guess I'll have to try again :)

Yes, I understand you feel this way.

Regardless, it is the case that PRANSWER is designed to imitate SIP use cases,
not some innovation that came out of the blue for WebRTC.

-Ekr
Received on Wednesday, 3 July 2013 11:41:26 UTC

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