After thinking about this some more, I'd say that there are signficant differences in regard to upward-compatibility:
- Proxies are upward-compatible because the design of SIP (and new SIP features) is done so as to minimize the need for proxies to understand the feature in order to allow two UAs that understand the feature to use it. - True B2BUAs are upward-compatible, because the UAs they are talking to can fall back to operation without any new feature. - The sort of devices people *call* B2BUAs, which are more "message-editing quasi-proxies", are much less upward-compatible, because they can't easily take advantage of either of the above SIP upward-compatiblity mechanisms. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
