How to check VoIP traffic legality?

[brightstar19]

How can I check that the VoIP traffic being sold isn’t “gray” or violating any laws?

[randomuser5]

I always ask the seller for some documentation, license references, or proof of legal status. Otherwise, there’s a big chance it’s a gray route.

[clevermind8]

I read reviews on industry forums—if traffic is illegal, someone usually mentions blocks or fines.