In a public system, you may wish to have "CallerId" have more meaning than From. In the Internet, you may not. When you transition from one to the other there can be issues, and I think that's what we are talking about.
In simple cases (single line residential), the public net will clearly use Asserted-Identity. The case that matters to me is an enterprise connecting to the PSTN. Does the PSTN trust the Enterprise proxy? That's easy, no. So, whatever comes from the Enterprise, whether it's in From or in Asserted Identity is going to be treated the same. The Public net won't know if the mapping between the user and the number is right or not. It will only verify that it's one of the assigned DNs to the Enterprise, and probably add an Asserted Identity to it. So, the question becomes, how much does the Enterprise care? If it does care, it might use Asserted Identity. This is a problem with the short term solutions because there is no trust across the boundary between the enterprise and the public network. Actually, I think it's probably not useful to use FROM, but the reason isn't security, it's simply that the UAC is not really the entity that knows the relationship between the user ID and the telephone number. So, I'll agree that my suggestion of FROM parameter is probably a loser. I'm annoyed that whatever we use, it looks like it has to be applied to every INVITE by the proxy (unless it knew FOR SURE that the call was not going to a gateway). Of course, this is not really the way it works now. What we actually do really is dependent on From. Gateways match From to a configured value. The outgoing callerId is that value. For small gateways, it's what port the call is placed on. Brian > -----Original Message----- > From: Jonathan Rosenberg [mailto:[EMAIL PROTECTED]] > Sent: Thursday, June 06, 2002 2:14 AM > To: Rosen, Brian > Cc: Tim Gronkowski; [EMAIL PROTECTED] > Subject: Re: [Sip-implementors] caller ID > > > > > Rosen, Brian wrote: > > Okay, but how would any proxy know, a priori, that it > should do this? > > Should every call have the Asserted Identity which is a phone number > > in case the call is forwarded to a gateway for calling into > a legacy > > system? Better to just make a header or enhance the FROM header > > with a parameter. > > Cool. Since its just a parameter of the From field, my UAC > can set it. I > think I'll configure my UAC to set it to your home phone > number, Brian. > Should be interesting. > > > -Jonathan R. > > > -- > Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Avenue > Chief Scientist First Floor > dynamicsoft East Hanover, NJ 07936 > [EMAIL PROTECTED] FAX: (973) 952-5050 > http://www.jdrosen.net PH: (973) 952-5000 > http://www.dynamicsoft.com > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
