I have been using localphone (dot com) for a few months while cruising and want to share my good experience.
Localphone provides you a local phone
number in your home country, and you can set your preference to have calls forwarded from that number to your roaming telephone (such as one with an in-country sim card) for pennies a minute. Quality is very good. Your contacts call you at your localphone number (or some other number that you then have forwarded to the localphone number) and your contacts never have to worry about where you are. Arrive at another country, pop in a new sim card, and go online and redirect your calls instantly.
I have no interest in the company. Its saved me thousands in roaming charges.