Nexmo, has been bought by Vonage for 2.5x revenue to get their 350 enterprise customers today, with one of the largest being UBER. If I was UBER's CTO I'd be concerned. The reason, integration of staff and technology.
When you look at it, Vonage bought revenue, a team and relationships. All those need to be integrated into the telco that is already having to do the same with the likes of SimpleSignal and Telesphere. So while this is a CaaS play, Vonage is not currently geared to be in the B2B customer service business, or deal with all the clients of Nexmo the way those customers are used to.
When large battleship size companies acquire nimble, fast to decide, and fast to implement type startups, it's the startup's customers who stop being the most important customer because the acquirer is. Just look at AddLive and their customers since the SnapChat acquisition. No forward movement on the platform and likely a soon to be wound down WebRTC stack.
This is no different than when GrandCentral was bought by Google and became GoogleVoice. The integration took almost 18 months to be Googleized....If I was Uber, I'd be looking for a new CaaS partner...