I have been using VOIP.ms for over 3 years now to replace my home phone service from the major telecoms (Telus/Rogers/Bell here in Canada). It has been very stable and a great price compared to other alternatives. I use it with a Grandstream HT801 and it's hard to beat the combo of these two.
To hook it up in my home, I simply unplugged the legacy telecom connection from the line coming into my home and plugged in the HT801 instead. Instantly all of my home phones started using VOIP.ms instead of my then current provider, after testing I simply ported my number over (for free) and haven't looked back since.
It has worked so well I felt I have hooked it up for each of my family members who have been saving significantly for years now. For every friend you refer, you both receive $10 in VoIP.ms credits! The more referrals you make, the more credits you earn! All the way up to $25 per referral.