No Subject

2. call-leg ID lookups in gateways are much faster now, since the tags and
call-ids are just strings. Matching is now case-sensitive string compares.
Much easier than URL comparison. 

3. Overlap dialing is easier. The reason we've had to send each digit as a
new call leg, is that we needed to change the To field and the request URI.
By definition, this meant a new call leg. Now, we can send all of that
within a single call leg. Much cleaner.

4. The Replaces draft benefits. We've already identified a need for the
Replaces header to identify the entire call leg thats being replaced. This
gets big when it carries two URLs, two tags, and a call-id. Now, we can
throw away the URLs. This shortens the header and makes matching of the
call-leg IDs easier.

5. It works with existing proxies.

THe main drawback, of course, is that this won't interoperate with rfc2543
UAs. Thats fixable with Supported; the UAC indicates Supported:
new-call-leg-id in the INVITE if it understands this. In that case, any
responses or re-invites that change the URLs include a Require:
new-call-leg-id. 

I fully admit that this may not be worth the pain. However, I'd welcome
comments from others on whether its useful to consider further.

-Jonathan R.


---
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
jdrosen@dynamicsoft.com                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com
 

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