sjinsjca

I cut my landline and went cold-turkey into VOIP last year.  My research led me to two providers who seemed well-recommended and fully-featured: voip.ms and callcentric.com.  Between the two, I chose voip.ms for its richer feature set and cost model, based on my usage patterns.
No regrets!  voip.ms was patient and supportive of me as a total noob, and I routinely got answers to my (webform-based) issues and puzzlements within minutes or a few hours max.  Now I have two homes using their service without a hitch, and with massive savings via my former landline solutions.
(I see another review here from someone complaining of voip.ms "ignoring" them for months.  This is totally 180 degrees from my experience.  I have rarely had such great service with a company.  Really, a superb company to deal with.  My friends to whom I recommended voip.ms relate similar tales of patient and near-instant support.)
In about eight months of use I have had a grand total of about about a half-hour's outage, about on a par with our former landline, and it was due to my ISP having a fire at a branch station.  Other than that, totally smooth sailing; no faults at all from voip.ms's side.
In both homes I'm using a Cisco/Linksys/Sipura PAP2-T analog phone adaptor and my old standard-issue telephones.  I also use the free 3CXphone app on my iPhone and iPad to call from wherever I happen to be where there's WiFi... including overseas.  It was really nice to be able to call back to the U.S. from London for a penny a minute.  Take that, usurious roaming fees.  And you, larcenous hotel phone!
voip.ms = Excellent sound quality + amazing service options + responsive support - something of a learning curve (which frankly I find to be a bit of fun). 
Totally recommended!