At first, VoLTE will be used to deliver "Rich Communications Services" (which look like something similar to what Voice over IP/Video over IP outfits offer today) rather than completely replacing narrowband voice. It will be awhile before Verizon is willing to commit to that, due in part to LTE outages in late 2011.
On the flip side is MetroPC, which has pushed VoLTE as hard as it could.
Then there's Sprint, which will stick to voice over 1x for the foreseeable future, but routes Direct Connect over IP. Sprint's latest DC incarnation seems quite similar to one facet of RCS over LTE.
Here's the press release: https://www.t-mobile.com/news/press/t-mobile-announces-un-carrier-next-on-july-16/
What: Now that Sprint is part of T-Mobile (NASDAQ: TMUS), the company will announce what’s next and how a supercharged Un-carrier will continue to change wireless for good.
Who: T-Mobile CEO Mike Sievert and other T-Mobile executives in a webcast hosted by Golden Globe and six-time Emmy nominee Anthony Anderson.
When: Thursday, July 16, 2020
Webcast at 8:30am PT (11:30am ET)
Live Media Q&A with execs immediately following
Where: Watch the webcast and listen to the QA at http://t-mobile.com/uncarrier.