Will Iphone 5s from Verizon work with an international GSM carrier?

I have an iphone 5s from verizon and will be traveling abroad for some time, needed to know if my iphone will work with a sim card from a local carrier abroad. I know at&t and sprint don't

Tell Verizon and they can modify your package for int'l travel and possibly give you a sim card of a partner carrier in that country to make it easier.
http://www.verizonwireless.com/...ogram.html

The biggest problem is Big Red and Sprint are CDMA signal based. ATT and most other foreign countries use GSM. So Verizon will have to modify the settings for you to make the dual bands work. Best luck.