Is Voltage Converter Necessary when charging iPhone 3GS in Amsterdam

I posted this question before and was told that all I needed to charge my iPhone in The Netherlands was a 2 prong plug converter (round pins) to convert my current plug to theirs. Apple sells a set for lots of countries, but I already have one for Netherlands. Discussions here said, just use the plug converter. Then I called Apple and they me that I also need to use a voltage converter in addition to the plug converter. I know USA voltage is 120 and Netherlands in 220 or 230. Will my phone burn out without a voltage converter? Apple says it might, yet they don't sell the voltage converters to go with the plugs they sell. They suggest Radio Shack, etc. What voltages will my iPhone handle? I don't want to buy another piece to carry over there if not needed. I keep getting different answers, even from Apple techs. Who knows for sure? Thanks for help.