Verizon utilizes GSM for LTE. ***ALL*** Verizon phones that are capable of LTE have a SIM CARD slot. With that being said, ***ALL*** Verizon phones are factory unlocked from the start.
****YES**** you can use a Straight Talk, Cricket, AT&T, T-Mobile, MetroPCS, TelCel, Boost Mobile sim in it.
Just be aware of the LTE phones WITHOUT GSM bands but still use a sim (a.k.a Verizon's LG G-Vista)
But the heavy hitters (S3, S4, S4, Note 2,3,4 G2, G3, Droid Series) They can be used with any sim, and run UP TO 4G (HSPA+) T-Mobile Sim in VZW will run LTE though. (and if you travel enough, your AT&T sim will occasionally pick up a LTE signal) wherever it is they use Band 4.
This is not the 90's, that whole VZW is CDMA only thing is done and over. (P.S. - Even Sprint has a few SIM capable phones that may be unlocked)
Please learn facts and stop steering people in wrong directions.
-MD, Xda