At ITEXPO I met with Applied Global Technologies (AGT), which was founded in the early 1990s, making it one of the oldest video conferencing solutions on the market, even if it isn't very well known. AGT offers managed video services and cloud video services that can be white labelled by service providers. They mentioned Level3 whitelabels their solution, as well as AT&T.
They mentioned they can easily whitelabel the mobile apps– simply provide logos to AGT and they manage the app development and approval with Apple on the service provider’s behalf– with the approval typically taking just a few days.
They support H.239 for desktop sharing and use SSL port 443 to solve NAT issues. There are many cloud-based video solutions such as Bluejean Networks, Vidtel, and others, so I'd be interested to see how they compare. Perhaps I'll do a comparative review at some point.