Please don't take this personally, but VOIPo has multi-thousands of customers and I would guess that if they were having the problems that you are having, they would have been long gone..

I have been around since the beta testing days and except for an occasional burp, have absolutely no problems. The only problems I seem to have are due to my changing modems-routers and ATAs.
Only then, when I mess up, do I suffer...and I only do this when my wife is out or I would really suffer.

Seriously, Tim has posted many times over the years to indicate that not every provider will work flawlessly for every user due to numerous reasons...some of them not correctable.
Years ago before VOIPo when I tried other providers, my wife would say to her friends...."Sorry, that's my husband's telephone system."
I haven't heard that for years now..