Can I use my iPhone internationally? I have an Apple iPhone 4 (model A1349) with Virgin Mobile service.  It works fine in the US but Virgin told me that it won't work internationally (i.e., calling within other countries or calling US from abroad).  

Is there anything that I can do with this phone or do I need a new phone and/or carrier?
The iPhone 4 came in two flavors: CDMA (Verizon, Virgin, etc.) and GSM (AT&amp;T, T-Mobile, etc.).

The GSM phone will work, however it will incur international roaming charges. Your CDMA version on the other hand will not work in most countries outside of the US.

I would recommend upgrading to the 4S or 5 as changing carriers will not change the radio in your phone.