This is all very confusing. The article I cited says the 4G Verizon phones are unlocked but my local Verizon store told me that they are locked. I would find someone with a different carrier with a sim card and borrow it and insert it into your phone and see it it asks for a code when powered on.
Alternatively try a sim card in Mexico and see if it works. If not, buy a cheap phone and use it there. There are stores in Europe that provide cheap phones for visitors and maybe the same is true in Mexico.
Let us know what you find out about locked/unlocked Verizon phones.