Can Verizon iPhone be used as GSM for overseas?

I've been currently on AT&T since forever and I travel internationally from time to time so having a GSM handset is required for me. But lately I am getting fed up with AT&T's shoddy service that I may switch to Verizon when the next iPhone comes out.

Question, will the Verizon iPhone be able to work on GSM networks in other countries? Since verizon uses CDMA, does that mean when I'm currently talking on my phone with someone will I stlil be able to receive notifications since that is coming over data? I heard that is the downside of being on Verizon is that DATA and VOICE cannot work together like on AT&T. That's the only killer for me, is that true?

Source: http://forums.macrumors.com/showthread.php?t=1406663&goto=newpost

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