IMO,
VoIP.ms quality and support are generally excellent. However, there are some reliability issues. Although they have servers in many cities and have never been completely down, the system for automatically switching users to a different server may not work, or is slow to take effect. So, users sometimes have to manually change to another server. If you search the BBR VoIP forum
http://www.dslreports.com/forum/voip , you can find lots of complaints.
In your case (using
VoIP.ms only for international outbound), it may not be so bad. If a call to Greece occasionally fails, you can just redial on Google Voice. Or, you could even configure your OBi with gateways for more than one
VoIP.ms server.
Quite a few providers, including Localphone, Rebtel, Zenofon, Voxbeam and Flowroute, give you a small credit at signup, usually good for about five minutes of calling, so you can evaluate quality without making a payment or providing any financial information.
The lowest cost option to Greece landlines (and most other places) is the Betamax companies. Quality and reliability are not as good as
VoIP.ms, but you may find them acceptable. Easyvoip is $0.005/min. Many of the others offer "free" calls to Greece, but the rules are complex for how many minutes you get, what payments are required, etc. A list is here:
http://backsla.sh/betamax .
Some of the providers mentioned have services that make it easy to call Greece from your mobile, or receive calls from Greece to your OBi or your mobile. If you will be making many calls to mobiles in Greece, you should factor those rates into your decision. Of course, the OBi allows you to connect to many providers, though you don't want to many, as it's an administrative hassle to maintain all the accounts, make payments, etc.
