If SipX would follow the RFC then it would send out 7 INVITE's totalling to 0+0.5+1+2+4+8+16=31.5 seconds of INVITE's. I don't think the client will wait that long, but the current SipX could be improved. If the client would terminate the call before the 31.5 seconds expire then I assume the Bye will be forwarded by SipX.
Paul Ari Sonesh <[email protected]> wrote on 08-11-2011 14:21:05: > > Tony, consider a scenario where most phones are connected to > wireless modems, and servers are on a public IP. There are > no gateways or trunk providers, just extensions are calling > extensions. There are many possible applications, but think > about application where care is provided to old people at > their homes that do not have connection to the internet > (most really don't), so the connection is via mobile data > network. > > The case of inherent (by design to save energy)latency in > opening a connection on a mobile data network is well > described in the following AT&T labs paper > http://www.research.att.com/articles/featured_stories/2011_03/ > 201102_Energy_efficient?fbid=0lDQwAs5gdi > (see the graphical depiction of the phases of data > connection setup). > > The conclusion is that it takes typically 2.4 seconds, > before packets start flowing, and including RT for DNS and > RT for first invite and ack it's 2.6 sec. I believe that > these numbers are "typical" sometimes less (and this is why > sometimes calls get through), and sometimes more. If this is > typical, i.e. a "mean" than probably doubling this number > would be "safe" timeout, i.e. 5.2sec. > > Also, in any case, if and when the SIPX gives up after a > timeout, it needs to send a disconnect message not leaving > the called extension in limbo (currently on timeout the > called phone doesn't stop ringing). > > _______________________________________________ > sipx-users mailing list > [email protected] > List Archive: http://list.sipfoundry.org/archive/sipx-users/
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