In the recent enormous thread "E.164 - who owns it" there was a lot of discussion on number URIs in 302 responses, and whether the UAS includes a tel URI, a SIP URI with the destination domain (B.com) or a SIP URI with the originating domain (A.com), and in the last two cases whether it is with or without user=phone.
What that thread failed to capture was the user's involvement in choosing the contact URI. Basically the UA either has to be pre-configured with the redirection URI to use if certain conditions apply to an incoming request, or the user takes some action when the request arrives. In either case, the user has two ways of selecting the URI: 1. From some sort of address book, call log or whatever. In this case the user reuses some URI that has been received by some other means (e.g., From URI from some previous communication, or vcard). Such a URI could be in any of the forms that are valid for making a call, including tel URI, email-style sip/sips URI, e.164-based SIP URI with/without user=phone. In the last case, the domain part will be whatever was received, which may be the local domain (B.com) but is unlikely to be A.com. At least if it is B.com, the B.com proxy could, if necessary, convert to something else (e.g., sip:[EMAIL PROTECTED]) before passing the 302 onwards. 2. By keying in the URI. The keying procedure is likely to be similar to what is used for keying in a URI when making a call. On a device with only a numeric keypad, the user will generally just enter a number, and the UA will convert this to some URI. This typically results in a URI of the form sip:[EMAIL PROTECTED], where number presumably should have some significance within domain B.com. In practice the number is probably a dial string, which would suggest inclusion of user=dialstring, although in practice this is probably rare. It probably doesn't matter. In any case, before passing the 302 onwards, the B.com proxy would need to covert this "dial string" URI into a URI meaningful outside its domain. This could be a tel URI or a SIP URI, although it is unclear how it could populate a SIP URI for passing to another domain. My point is, the UAS is typically not in a position to choose the URI format, but the B.com proxy, when passing the 302 onwards outside its domain, will have to take care to use an appropriate format, i.e., it would have to convert a SIP URI with the B.com domain into something else, e.g., a TEL URI. Any other form of URI probably has to be passed on unchanged by the B.com proxy. John _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
