People have to acknowledge what the company considers a face to face call. Signatures must be witnessed. Those are the rules. At times, an outside company is hired to spot-check face to face calls in order to see; 1) if the rep was there, 2) what products were detailed and 3) if the hcp recalled the message. A red flag goes up if too many negative responses are generated. Lastly, offices receive messages all the time asking to verify a signature. This "random signatue audit" is usually done by pulling all the interactions with samples on a given day. If any come back negative, then a case if opened.