You could have a point there but wouldnt calling and texting still work?
You sure its not blacklisted?
Here is the simplest thing you need to know:
Locked iPhone = Display's "Invalid SIM" Gray screen
Blacklisted / Barr'd / Bad IMEI iPhone = "No Service" with any SIM in the phone, if this "No Service" doesn't go away even after restoring the iPhone then might want to make sure its not blacklisted as that is the only reason it would display the "No Service" even after restoring.
All Verizon iPhone 5 / 5C / 5S / 6 / 6 Plus = Factory Unlocked, Having owned each model to-date I can confirm this 100% (Currently using a 6+ Verizon on AT&T) plus with friends in the mobile unlocking business.
All iPhone 5C / 5S / 6 / 6 Plus from Verizon support 100% T-Mobile 1700 AWS 4G and LTE out of the box identically with 0 difference when compared to the ones purchased from AT&T / T-Mobile
All iPhone 5C / 5S / 6 / 6 Plus from Verizon support 100% AT&T 4G + LTE out of the box identically with 0 difference when compared to the ones purchased from AT&T / T-Mobile
iPhone 5 (A1429*) from Verizon = 3G/4G on AT&T and 3G / 4G on T-Mobile (In 1900MHz Refarmed areas only = usually within city limits)
*iPhone 5 A1429 = Sold by Sprint and Verizon and Sprint one will always say "Invalid SIM" as its not possible to unlock it and use it on domestic carrier's --- international unlock = next to impossible as well.
Hope it helps, remember guys when your iPhone constantly displays "No Service" -- #1 thing to look at is blacklist status don't jump to conclusions about lock status because again...no locked iPhone will just display "No Service" it will clearly state "INVALID SIM"