Next month, I will be traveling to the Balkan region of southeastern Europe with an unlocked iPhone5. I would like to obtain a SIM card that could work for telephoning throughout that entire region, including the 7 countries of Serbia, Romania, Bulgaria, Macedonia, Albania, Montenegro, and Bosnia-Hercegovina. Many of the European SIM cards that are available online, like Vodaphone and Orange, do not include all of these countries (usually they only include the EU countries of Romania & Bulgaria).
The Technology for Travelers Website, compares available cards that seem to include these Balkan countries:
The site reviews these brands: OneSim, WorldSIM, KeepGo, GoSIM, KnowRoaming, and GigSky. Has anyone used any of these cards in the Balkan region? Does anyone have a recommendation for a SIM card that would include reliable coverage, even in rural areas of the above listed Balkan countries? Is there any problem associated with obtaining one of these cards online in the U.S. and then bringing it with me to Europe? Is there any way to test whether the SIM card will work or not before I leave the U.S?