Pen recorders and phone records

I am confused about the necessity for this if the phone companies routinely record this information anyway. Is this just an archaic and obsolete terminology, and what really happens is that the phone company will give already-existing phone records to authorized officials?

Hal, I'm not sure, but a pen register would record all dialing codes (touch tone), not just those used to make the first leg of the call. Voicemail, multihop calls, etc come to mind. Eric Blossom