It will not work on Verizon unless he bought a Verizon version. All Verizon iPhones with LTE are required to be unlocked per the FCC. Some T-Mobile versions are unlocked, but Verizon only allows the Verizon version of the iPhone to work on their network.
I'm not sure if that's accurate. I believe all iPhone 6s are created equal, and as long as they are unlocked, any iPhone 6 should work on any U.S. carrier (with the possible exception of Sprint).
I am sure it is accurate. The iPhones that are sold as Verizon phones have their IMEI/MEID numbers in Verizon's system. If you buy a non-Verizon unlocked model, it will not work because the IMEI/MEID numbers are not in Verizon's database.
I am sure it is accurate. The iPhones that are sold as Verizon phones have their IMEI/MEID numbers in Verizon's system. If you buy a non-Verizon unlocked model, it will not work because the IMEI/MEID numbers are not in Verizon's database.
Some people have put a Verizon SIM in an unlocked/T-Mobile version and gotten SOME of the features to work, but it typically causes ongoing problems. If you're not in an LTE area, it won't fall back to CDMA for calls or data. Visual Voicemail doesn't work. I've seen other random issues reported.
A Verizon iPhone 5, 5s, 6, and 6 Plus will work on any LTE network because it is sold unlocked, per the FCC.