bliss-1----Page:2
1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16 

While this approach brings great flexibility and generality, it complicates interoperability. Without any kind of standardized definition of a particular service, each implementation creates its own definition and corresponding set of call flows and primitives used to realize this service. In practice, this has resulted in a poor track record for interoperability, especially for features which make assumptions on supported SIP extensions and behaviors from other elements.
PPT Version