Assuming that you have caller-ID, and know it’s not your friends or your mom, you answer: “Trixie’s Call Girl Service. Press ‘one’ for an appointment. Press ‘two’ if you are seeking employment. Press ‘three’ if you are a law enforcement officer.”
Then, no matter what they say, or what touch-tones they press, repeat the above.
After they’ve started, you say, “This is good! Hang on!” Make a clicking sound, then say, “The rest of this call is being recorded for quality assurance.”
If they stumble or say anything, jump on it suspiciously. Interrupt more and more, and begin to ask for their name and callback number and the name of their supervisor. If you wish, pretend to yell to someone offline, saying, “Joyce! Pick up line six. It’s one of our guys. You won’t believe this!”
Interrupt them and demand to know how they got this number. Before they can reply, tell them to be quiet and listen, because there’s not much time.
Tell them federal agents are en route to their location, and to follow your instructions to the letter if they want to avoid being shot. Tell them to shut down their computer and all other devices in their office, hang up and unplug the phone, then to kneel down in the middle of the room. They are then to cross their ankles and place their hands on their head and stay that way until the agents arrive. Then hang up.