isip-3----Page:4
1  2  3  4  5  6  7  8 

Pervious draft proposed to piggyback policy operations onto INVITE – OK – ACK cycle.
But this proved to have two major problems:
Requires that both UAs support policies.
Does not support “asynchronous” policies.

This makes the piggyback approach unsuitable as a general purpose model!
Session-Specific Policies
PPT Version