I just went to Norway with my United Mobile sim. I told my wife to use the VOIP account since it was likely going to be the cheapest. The VOIP was charging .275/Min.
She had to make some calls to me on the home phone for which our carrier is United Carrier Networks (UCN). I expected that to be really expensive.
I just got my bill...and to my complete surprise, all calls to my United Mobile number were charged at .06 per minute!
NOW we are talking