How to find out what phone my gf is using i am in usa she is in the Philippines?

ok she told me she sold the phone a long time ago. But i am really sure she still has it and still using it. So is there a way for me to find out what cell phone she is using? I do not have a cell phone i only a laptop and that is all. Any idea how to do this? I am in USA she live in the Philippines and she is still there. Her phone that i am sure she still has and use is Nokia Lumia 520 3G Phone. Thank you if you have a way. And asking her friends or family will not work

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