The customer service and tech support…
The customer service and tech support is fantastic!! 5 stars! The actual phone system has had some glitches that shouldn't be happening, like they will not work on our newer, faster internet service for the most part. And there are technical issues at the home "central station" every other month or so hurting the flow of business for hours on end. It only happens for a few hours, but we can't have that downtime. Otherwise, we are very happy with OnSip