Is Verizon iPhone 5S unlocked for international carriers?

I'm traveling abroad to Taiwan for a month, and I'm just wondering if my iphone 5s is already unlocked so that I can actually use the sim card from carriers in Taiwan or do I have to call Verizon to have them unlock it.

( 2 years ago when I traveled out of US, I had to call verizon for a "international unlock" on the iphone 4S i had, do I have to do the same for iphone 5s?)

No. They are not already unlocked for foreign travel. You'll do the same thing just like the 4s. Best luck.

All new Verizon phones are unlocked and on dual GSM CDMA. Yes it will work, but don't take my word for it, get an assurance from the Verizon store before you buy it that it will work on GSM overseas.