VOIP got a bad rap 5-10 years ago, mostly in the home marketplace with poor quality devices and low bandwidth. It was deserved, but people holding onto that impression are just out of date with the state of current technology and bandwidth.
I've got 1100 users in 12 US locations. We're in our 6 month of full deployment and have no quality issues. You can find our case study here if it helps https://www.ringcentral.com/whyringcentral/casestudies/world_vision.html
6 months later as a company we have zero regrets. It works well, it's saved us significant monies, which let's us send more to the field for our humanitarian work, which is great.