An anti-telemarketing program uses the calling party identification of an incoming call to determine if the call is a telemarketing call by accessing a telemarketing database. The incoming call can be identified as a telemarketing call by direct correlation with a known telemarketing number or by indirect correlation by not being included within a list of known non-telemarketing numbers. If an incoming call is identified as a telemarketing call, and no override condition is set, the call will not be allowed to ring through to the desired phone line; instead, it will be terminated by a call progress tone or by a notification that the desired phone line does not accept calls from telemarketers. If an incoming call is not identified as a telemarketing call, it will be completed, and if it is from a telemarketer, the party receiving the call can designate the calling party identification from the call as belonging to a telemarketer. The designated calling party identification can be added to the telemarketing database when a preselected criterion for addition, such as independent verification or designation of the same number by multiple parties, is met.