I have a Verizon Z30 and it came factory unlocked (at least for GSM). It worked perfectly with an international carrier's SIM while traveling last week (got 4G).
Verizon Z30s and most Verizon phones are sold unlocked. Since they got the 700 LTE spectrum, they made an agreement with the FCC to sell all there phones unlocked, and they are doing this. I believe it started with the first 4G LTE phone they offered.