Re: [rtcweb] Bridged line appearance? (Re: Usecase & architecture: Browser application with separate webserver & voipserver)
Paul Kyzivat <pkyzivat@alum.mit.edu> Wed, 07 September 2011 23:36 UTC
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Date: Wed, 07 Sep 2011 19:38:25 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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To: Mary Barnes <mary.ietf.barnes@gmail.com>
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Subject: Re: [rtcweb] Bridged line appearance? (Re: Usecase & architecture: Browser application with separate webserver & voipserver)
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Mary, My assertion that the analog implementation of these features was easy was in reference to support of multiple "extensions" on a single analog line, as Matthew mentioned earlier, where shared line appearances and bridging come "for free", though with some limitations. I realize that it got considerably more complex with analog PBXs. Thanks, Paul On 9/7/11 2:24 PM, Mary Barnes wrote: > Just one comment below [MB]. > > Mary. > > On Wed, Sep 7, 2011 at 10:18 AM, Paul Kyzivat <pkyzivat@alum.mit.edu > <mailto:pkyzivat@alum.mit.edu>> wrote: > > Matthew, > > Good summary. > > I agree that webrtc provides flexibility in how to implement the UI > portions of these features with generic webrtc clients. But it > doesn't make these features trivial to implement. In particular, the > bridged line appearance still requires that a conference be > established. With generic rtcweb clients, that probably means a > central mixer. Setting that up is relatively easy if there is a > central media termination point in rtcweb server, and it *has* mixer > capabilities. > > My point is not that rtcweb doesn't help with this case - just that > these features that are so trivial in analog telephony just aren't > so simple with voip, no matter how you do it. > > [MB] These features we not trivial in analog telephony by any means > (speaking as someone who wrote LOTS of code for these ancient telephony > systems). IMHO, it's this misconception that the services and > functionality in analog telephony systems was simple that's led to the > difficulty in getting any operability for these services defined for > SIP. Many of the legacy telephone systems were no more designed for a > host of complex services than SIP was. However, it would have been nice > if services had been considered in the initial design for SIP. While > there is the concept that many services can be accomplished with basic > SIP building blocks/headers, we have way too many situations where this > has proven to not be at all simple. But, I don't think SIP/VoIP is any > worse off than were the legacy systems. And, I agree with Paul there > isn't any magic dust that will make it any easier for RTCWEB to support > these features. [/MB] > > > Thanks, > Paul > > > On 9/7/11 10:16 AM, Matthew Kaufman wrote: > > On 9/7/2011 4:10 AM, Harald Alvestrand wrote: > > > Since more people than I may be confused, I'm forking a > subthread... > > what is a bridged line appearance, and why is it hard to do > in SIP? > > My terminology cache is totally blank. > > > Key system (and home phone) emulation requires two things that > are hard > to do (because there's no final specification, not because it is > impossible) (and because there's 3+ alternatives, and almost no > phones > implement more than one of them) in SIP: > > 1. Shared line appearance > > This is where you can be on a call on one handset, see that the > line is > in use at the other handset. Place the call on hold at the > first, pick > it up at the second. > > In business PBX cases, this is used for executive/assistant > cases. In > key system emulation it is used for "Bob, pick up the call > holding on > line 3". And for home phones it is the usual "put the phone on > hold in > the kitchen, pick it up in the den." (My wife wanted this > functionality, > so I had to add proprietary support for shared line appearance on my > home PBX.) > > 2. Bridged line appearance > > This is where you can be on a call on one handset, see that line > is in > use at the other handset, and pick up the second handset to join > the call. > > In the business PBX and key system case this is sometimes used for > supervisors to join a call to help, but the real common case is > the home > phones... "kids, go pick up the extension in the living room and > talk to > grandma." > > With POTS, this works by simply paralleling two handsets on the same > copper pair. For SIP it requires everything shared line > appearance does > *plus* automatic barge-in + conference on pickup. > > The BLISS WG has been working, for a long time, on taking the > various > interim proposals and creating a standard out of them, but we're > still > not there... and yet without it, there's no way to use phones > from two > different vendors to accomplish this. > > Whereas with WebRTC implemented *without SIP*, it is fairly easy to > build a web app that runs on multiple browsers from multiple > vendors and > implements this. > > So this type of ability to innovate and implement applications > without > going through the standards process is why we *definitely* don't > want > SIP baked in to the browser. > > Not to be confused with the arguments against SDP offer/answer, > which is > only slightly affected by the above use cases (in that you can do > smarter things at the bridge for bridged line appearance if you > aren't > doing a reinvite/re-offer/re-answer but instead have on hand all the > capabilities of the first device when the second goes to join). > > Matthew Kaufman > _________________________________________________ > rtcweb mailing list > rtcweb@ietf.org <mailto:rtcweb@ietf.org> > https://www.ietf.org/mailman/__listinfo/rtcweb > <https://www.ietf.org/mailman/listinfo/rtcweb> > > > _________________________________________________ > rtcweb mailing list > rtcweb@ietf.org <mailto:rtcweb@ietf.org> > https://www.ietf.org/mailman/__listinfo/rtcweb > <https://www.ietf.org/mailman/listinfo/rtcweb> > >
- [rtcweb] Some misunderstandings about <Usecase & … Nguyen Duong Tuan
- Re: [rtcweb] Some misunderstandings about <Usecas… Ravindran Parthasarathi
- Re: [rtcweb] Some misunderstandings about <Usecas… Bernard Aboba
- Re: [rtcweb] Some misunderstandings about <Usecas… Nguyen Duong Tuan
- Re: [rtcweb] Usecase & architecture: Browser appl… Ravindran Parthasarathi
- Re: [rtcweb] Usecase & architecture: Browser appl… Matthew Kaufman
- Re: [rtcweb] Usecase & architecture: Browser appl… Ravindran Parthasarathi
- Re: [rtcweb] Usecase & architecture: Browser appl… Matthew Kaufman
- Re: [rtcweb] Usecase & architecture: Browser appl… Ravindran Parthasarathi
- [rtcweb] Bridged line appearance? (Re: Usecase & … Harald Alvestrand
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Matthew Kaufman
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Matthew Kaufman
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Cullen Jennings
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Cullen Jennings
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Tim Panton
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Paul Kyzivat
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Mary Barnes
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Matthew Kaufman
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Matthew Kaufman
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Matthew Kaufman
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Paul Kyzivat
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Paul Kyzivat
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Asveren, Tolga
- Re: [rtcweb] Bridged line appearance? (Re: Usecas… Paul Kyzivat