I use two solutions. I recently canned RingCentral becuase of too many problems.
To let you know, this is not small amount of calls, I have a call center who uses these services for a few of their seats each week to test out new campaigns (its cheaper for a small business than a pbx).
MagicJack, - I cannot believe it but it works pretty darn good, I use this for my home.
Skype - OMG, I cannot believe how clear this call is. It is so clear that I purchased the unlimited ($3) and an inbound phone number ($18 for 3 mo). This actually work so good that we use it a lot in the office. Be aware that unlimited is not really unlimited. They caps us at I think 100 outbound calls per day, after that it charges us. But it hasn't been an issue.
All of this I use through my google voice (which is NOT a VoIP). The call first originates on GV, then transfers to either magic jack or skype depending on which one answers it first.