The reader may recall that the FBI and other government agencies have been active lately trying to do things like get their own encryption technology used in all telephones, and getting it made legal to obtain reports of who called or was called by any given person in a given period. They are only asking for it to be made legal to do what they are already doing illegally, from a single central office, with a few keystrokes. They want to use in court what they are now using in investigations. So, we can conclude that federal agencies know who is communicating with whom. This doesn't have to be done at a link in the network.
Any user can do it.
Sooner or later most people will provide some identifying information, to someone, somewhere, and it will get picked up. So, one might be careful and not provide identifying information. Small, local or regional providers may be somewhat secure against outsiders obtaining copies of account information, but the larger, nationwide providers are not. Some even sell the information to the open market. If you provided any identifying information in obtaining the account, such as a credit card, and the provider is one of the larger ones, then you can assume that the federal agencies have the information.