I wonder how efficient VoLTE will be. I love the idea that my carrier is just a dumb pipe that I use to make VoIP calls with whatever service I desire but from what I have heard that may be a poor engineering decision. I remember a Qualcomm (its their baseband chip in the iPhone 4S and 5) engineer state that there have been decades of research into getting the highest # of calls and best call quality per Hz of OTA bandwidth. The engineer went on to say that operating at a packet level is too high of an abstraction if you want to squeeze the most out of the cell network. He stated that you must drop down into lower, more niche/optimized layers to really match the efficiency that they already have achieved on GSM/CDMA voice.