[reSIProcate] InviteSession spec questions

[Jason Fischl]

Hi Robert and Rohan,

Derek and I have a few questions that shouldn't take you too long but we 
are a bit blocked on these issues right now.

Is it valid to send a provisional response (1xx) to a reINVITE? If so, 
what would this mean? If 1xx to reINVITE is allowed, does this mean the 
UAC would ever want to send a CANCEL to a reINVITE?

What should dum do if acting as a UAC it reINVITEs, doesn't get a 
response (other than 100) and the application asks to end the invite 
session. My take is that it should create a timer (64 x T1), wait for 
the response to the reINVITE or the timer to fire (whichever comes 
first) and send BYE.

Does the application need a way to end specific ClientInviteSessions 
that are in the early state? Consider an INVITE that forked and created 
two ClientInviteSessions with 1xx. The application can send a CANCEL 
which will end both usages. If we provide an end interface on the 
specific usage, should it send a BYE on the early dialog? Otherwise, 
what will it mean to end a specific early dialog?

I am proposing that a usage NOT be created when a 100 is received. The 
usage(s) would be created after 1xx or 2xx is received. If a CANCEL is 
sent and no 487 is received, who should be responsible for cleaning up 
the ClientInviteSessions in the early state? Presumably, the DialogSet 
could create a timer and clean up any remaining usages. How long should 
this timer be?