You can buy a cheap ish Internet capable mobile and use it in a free WiFi enabled place or a cheap laptop running Tails or Whonix and could just literally bin it after the call or email, so they really are just pissing in the wind to try and catch anyone with a knowledge of security let alone hacking systems, with a mandate to circumvent and evade for whatever reason, I'm sure any good CEH could make the info come from Langley's own network.
Is it just the scare factor then, justifying their existence, monetary backing and keeping their cushy jobs?
Seems like it judging by their outstanding accomplishments so far.