Are all Verizon's LTE/GSM phones actually unlocked?

I know Verizon iPhones are unlocked since the iPhone 5 (using it myself). However, I can never seem to get any real verification for other Verizon phones (Android, Windows Phone, etc). I want to see real confirmation (not just "it should be," or "according to the agreement with FCC, they should be," etc. Of course, no tech blogs ever bother covering this, so I have to rely on information from forums.

If you have a Verizon LTE/GSM phone, and you have verified it as unlocked (either by using it on AT&T/T-Mobile, or overseas), please share your findings.