Please check with your institution for specific policies and processes but, my understanding is that these "referral leads" must be handled slightly differently than when information is requested directly from the interested party. Specifically, the individual would not fall under the provision for calling within a certain time of initiating contact since the fact you have their name came from another party. If the individual is on a DNC list, you must follow related rules. I have seen several suggestions for handling this including: having the student who referred the new prospect call you or have them bring the referral to the school for a visit. I have also seen schools handle an initial communication with a referral via other methods such as email or regular email.