What I do is have google voice take over my sprint phone number (essentially porting my number to google). Now when I login i can select which phones ring and whicn phones don't. So for example since I have unlimited international data on my sprint phone, but NOT calling ($2/minute avg for calling), I don't want my number to ring my normal phone - so i turn it off.
Then I add a skype number to google voice and have it ring that, that way I can have skype on my iphone going over the unlimited data, and I have skype forwarding to my local SIM card, so that my dumb phone rings as well as skype on my iphone, whenever someone calls my US number.
In addition I can use any computer to answer a phone call via skype.
Been doing it like this for years, works great.
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