Blacklisting is the process of rejecting a particular telephone number. There will be 2 options for blacklisting. The first option will send the caller to voicemail. They will then have to leave a message in order to reach the customer. The second is total blacklisting which the caller will hear a busy signal. They will not have the option to leave a message. To keep things simple, the blacklist method will apply to all of the blacklisted numbers.