I'm still reading this lengthy stream of messages, but I can see point beingmade. It's like the old system of ringing home when you have successfullycompleted a flight, with the understanding that your wife will get the messageof safe arrival but not pick up the phone and get charged for it. So similarlythe two users could agree (with the help of UAs containing hacked software) toexchange SDP, reject the addition of video at the signalling level, then carryon with video anyway. The service provider obviously has to protect its interests by monitoring themedia streams being exchanged.There's nothing you can do at the SIP level todefend against deliberate violation of the semantics of the protocol. gao.yang2@xxxxxxxxxx wrote:> I just mean that B can pretend to reject the adding vedio modification > request. But A and B use vedio after the rejecting 4xx.> > That is yhe illegal situation.> > > > > > > "Christer Holmberg" <christer.holmberg@xxxxxxxxxxxx> > 2009-02-27 18:02> > 收件人> <gao.yang2@xxxxxxxxxx>> 抄送> "Gonzalo Camarillo" <gonzalo.camarillo@xxxxxxxxxxxx>, <sipping@xxxxxxxx>, > <sipping-bounces@xxxxxxxx>, <wang.libo@xxxxxxxxxx>> 主题> RE: RE: Re: ??: Re: ??: Re: ??: Re: ??: Re: ??: Re: ??: Re: ??: > Re: Closing the offer/answer rollback issue> > > > > > > > Hi,> >> If B do not do so, then A and B can use it illegal. That's what I said > times :) > > I am not sure I understand...> > If B doesn't want to use video, he should remove it (no matter how it is > done). > > If he doesn't remove it, it will be used, charged for etc. I don't know > what is "illegal" by that. > > Regards,> > Christer > > > > > > > "Christer Holmberg" <christer.holmberg@xxxxxxxxxxxx> > 2009-02-27 17:31 > > > 收件人> <wang.libo@xxxxxxxxxx>, "Gonzalo Camarillo" > <gonzalo.camarillo@xxxxxxxxxxxx> > 抄送> <gao.yang2@xxxxxxxxxx>, <sipping@xxxxxxxx>, <sipping-bounces@xxxxxxxx> > 主题> RE: Re: ??: Re: [Sipping] ??: Re: ??: Re: ??: Re: ??: Re: ??: Re: ??: Re: > Closing the offer/answer rollback issue> > > > > > > > > Hi, > > If preconditions are met for the video stream, but UE-B then decideds that > he doesn't want to video, an alternative to "late commitment" is for UE-B > to send a new re-INVITE/offer to UE-A and remove the video. > > Regards, > > Christer > > > From: wang.libo@xxxxxxxxxx [mailto:wang.libo@xxxxxxxxxx] > Sent: Friday, February 27, 2009 11:25 AM> To: Gonzalo Camarillo> Cc: Christer Holmberg; gao.yang2@xxxxxxxxxx; sipping@xxxxxxxx; > sipping-bounces@xxxxxxxx> Subject: 答复: Re: ??: Re: [Sipping] ??: Re: ??: Re: ??: Re: ??: Re: ??: > Re: ??: Re: Closing the offer/answer rollback issue> > > Hi Gonzalo Camarillo, > > If UE-A wants to communicate with UE-B by video, but UE-B only want to > communicate by audio. > and if they uses the new SDP, when pre-conditions met, UE-B will send > his/her videos regardless > of UE-B's willing. > And if UE-B never send his video although the pre-conditions are met, > then UE-A will be puzzled why > he/she is charged for vedio while receiving NO vedio from UE-B. > > I think this is a operational problem that we have to solve too. > > regards, > Eric > > > > Gonzalo Camarillo <Gonzalo.Camarillo@xxxxxxxxxxxx> > 2009-02-27 17:10 > > > 收件人> wang.libo@xxxxxxxxxx > 抄送> christer.holmberg@xxxxxxxxxxxx, gao.yang2@xxxxxxxxxx, sipping@xxxxxxxx, > sipping-bounces@xxxxxxxx > 主题> Re: ??: Re: [Sipping] ??: Re: ??: Re: ??: Re: ??: Re: ??: Re: ??: Re: > Closing the offer/answer rollback issue> > > > > > > > > > > Hi,> >> Also If pre-conditions are met,and re-INVITE fails, UEs could use the >> new SDP.>> This solution will give someone a way to escape charging. >> For example, if UEs use audio at the first time,>> then one of them raise a re-INVITE with a SDP carrying both audio and >> video,>> after the preconditions are met, then the other rejects the re-INVITE,>> but they can communicate with both audio and video after all.> > No, if they negotiate video and the preconditions are met, they will be > charged for video, regardless of what happens with the re-INVITE.> > Cheers,> > Gonzalo> > > --------------------------------------------------------> ZTE Information Security Notice: The information contained in this mail is > solely property of the sender's organization. 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