Here's the punchline that most of the writers in the industry don't discuss. IMS is an interoperability standard, but everyone implements their own version. Th

Here's the punchline that most of the writers in the industry don't discuss. IMS is an interoperability standard, but everyone implements their own version. The original intention of IMS was to provide a method of dealing with non-IP systems as IP (Particularly SS7 related functionality). The issue is that SS7 was the last pre-divestiture routing system (thus it was the last ubiquitous standard), and there can be no consensus in the industry anymore with respect to standardization. So why no VoLTE? Because there isn't a standard that everyone is willing to implement, and there probably never will be. IMS is different everywhere you go.