Subject: RE: [Sip] The Problem with PRACK

From: "Christer Holmberg \(JO/LMF\)" <[email-masked]>
Date: Thu, 16 Mar 2006 23:15:38 +0100

Hi Dean,

I may missunderstand you, but are you saying that in your world (the
non-PSTN one, I assume) it is ok if the phones ring even if there are
not enough resources to establish the calls?

Regards,

Christer 

-----Original Message-----
From: Dean Willis [mailto:[email-masked]] 
Sent: 16. maaliskuuta 2006 0:25
To: Juha Heinanen
Cc: Christer Holmberg (JO/LMF); [email-masked]; Brett Tate
Subject: Re: [Sip] The Problem with PRACK

On Mar 14, 2006, at 4:55 PM, Juha Heinanen wrote:

> Christer Holmberg (JO/LMF) writes:
>
>> When 100rel is used it gives a possibility to ACCEPT an offer, and 
>> send an answer BEFORE 200 OK.
>
> why is it important for the UAS to accept SDP offer before accepting 
> or rejecting the invite and why it is important for the UAC to be sure

> that UAS has accepted the offer before accepting or rejecting the 
> invite?
>
Because people adopted the user-expectations of the PSTN as requirements
(a mistake, I believe).

In this model, your phone doesn't ring unless there are resources
available on the net for the call leg that will exist when you answer.

So the model is: 1) Locate target. 2) Establish resources. 3) Notify the
user of the target. 4) Talk.

Of course, this could all have been done more easily my having first
done an exploratory INVITE that returned a contact, using RSVP or NSIS
to establish media resources to the contact, and then sending the INVITE
to the contact. But people somehow though that doing it in a different
order would make the resource management easier. In general, it didn't.

--
Dean

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---

From: Juha Heinanen <[email-masked]>
Date: Fri, 17 Mar 2006 00:30:35 +0200

> not enough resources to establish the calls?

christer,

for resource reservation by SIP UAs, you don't need anything that is not
already in RFC3261 as i have shown in earlier messages.

-- juha

---

From: Dean Willis <[email-masked]>
Date: Thu, 16 Mar 2006 17:39:17 -0600

Ok, this has gone on long enough. You people aren't even reading  
anymore.

--
Dean