I'm not sure what actually would be the method for that. I think there are a few different things, depending on the technology you're implementing. Sometimes it would be that the provider can provide the information, or they can design it. In a lot of cases they're designing it so that they don't actually see the data that traverses the network, and they're making explicit design choices. How you would address it depends on what you're actually trying to solve there. It could be technologically complex in some cases and it could be really easy for lawful access types of things.
On September 20th, 2018. See this statement in context.