From: =?utf-8?q?I=C3=B1aki_Baz_Castillo?= <[EMAIL PROTECTED]> Hi, I've realized that my carrier's Nortel CS2K requires me an INVITE to a number in format "00XXXXXXXX..." for international calls.
That is not surprising, as "00" is often used as the international dialing prefix. Is replied with a "487: Request Terminated" by Nortel (also I'm 100% sure that 487 shouldn't be used for this purpose). As Bob Sparks replied (but possibly not to this thread), a UAC must be prepared to receive a 487 response to any request, because it could result from a CANCEL generated by an intermediate proxy. Of course, in this situation, a 487 is not a *good* response, and the service should be responding 404/410/480 to invalid request-URIs. Is it ""normal""? Why the hell does a softswitch require *anything* in the "To" URI? (except the To_tag XD). As Paul mentions, a SIP agent shouldn't *require* any particular To-URI, because such a requirement is a constraint on *every other SIP device in the universe*. Of course, if the UAC recognizes the To-URI, it may make a decision based on the implied knowledge about the intention of the UAS. But it should never *reject* a call based on the To-URI. IMHO, the confusion regarding the use of the To-URI comes from assuming that SIP calls will be "telephone-like", that is, that the UAC will specify a URI that will route to one specific UAS which possesses that URI as a "name". (Or at most, a small set of UASs which are directly managed by a single proxy which is authoritative for that "name".) In reality, SIP call routing is more like e-mail lists, where a single URI may fork to several URIs which in turn fork again, and the different forking proxies may be under different administrations. In general, *no component* of the call is authoritative for, or even has global knowledge of, the routing of the call. In particular, the UAC has no reliable information about the destinations of the call until it receives responses from the UASs. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
