Subject: RE: RE: draft-ietf-mmusic-sip-session-timer-00.txt

From: Sean Olson <[email-masked]>
Date: Fri, 12 Feb 1999 13:49:33 -0600 (CST)

> 
> > [Ernst Horvath]  Not quite true - for the gatekeeper, ITU-T  
> > Recommendation H.225.0 specifies the Disengage message for the regular  
> > termination of a call (i.e. the gatekeeper is informed immediately upon  
> > termination), but there is also the Status request/report procedure to  
> > check the status of an end point. If exchanged at regular intervals  
> > (say every n seconds, while a call exists), the gatekeeper will notice  
> > the "death" of an end point with a delay of at most n seconds.
> > 
> 
> Which means that if you want to maintain the billing accuracy that is
> popular in today's PSTN, you'd have to set this frequency to one second...
> Has anyone analyzed the scalability of this ? How big is the PDU of the
> status message ?

This assumes the best case scenario w/no re-transmissions and perfect
reliability of the status requests (which does not exist for UDP SIP 
communication). The bottom line seems to be that if you want to charge
on a time usage basis, you MUST have control of the media stream which is
outside the scope of SIP itself.

Sean Olson

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