> [JRE] This is a pointless exercise if it can't be deployed without > fixing SIP intermediaries that are out there at present, and many of > these are B2BUAs. This is similar reasoning to that which says that it > has to work with the majority of UAs out there at present. > There has to > be a good chance of the mechanism working in the majority of > inter-domain situations, and sadly that will nearly always involve > B2BUAs of some form, and sadly this means a lot of things in SIP > messages get changed. We can't do much about B2BUAs that are > deliberately trying to stop things working, but we should at least try > to take account of B2BUAs that are going about their legitimate > business. Otherwise this will be yet another SIP RFC that never or > rarely gets deployed.
Let's steal a pagebook from the PSTN, circa the early 1990's, when disable-echo-cancellation tones were introduced. As everyone probably remembers, they were necessary for the >9600bps modems and fax machines. At the time, no PSTN equipment understood the disable tones so nobody could use their fancy 14.4kbps modem at 14.4kbps. But as time went on more PSTN equipment understood the disable tones and eventually you could almost always get a >9600bps speed connection. It did not happen overnight, and did not happen immediately. People that bought the faster modems were often unhappy they could not use the faster speed. But the specification was written, intermediaries (Service Providers) agreed it caused them no harm, eventually the intermediary equipment understood the disable-echo-cancellation tones. Briefly, world hunger was solved. If that situation doesn't ring with some familiarity, there are many other situations where where intermediaries had to upgrade in order for the end user to benefit: unleaded gasoline; airport runways long enough for passenger jets. I'm sure more creative people can think of other situations where this worked well. Obviously there are zillions of counter examples as well (e.g., hydrogen powered cars are not viable due to insufficient numbers and poor distribution of hydrogen fueling stations; supersonic flight over continents is not viable because the people living on the continent do not generally enjoy the supersonic boom). -d _______________________________________________ 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
