Apparatus and method for identification of spam

In general, the subject matter described in this specification can be embodied in methods, systems, and program products for identifying telephone spam. An indication of an incoming telephone call and a calling device telephone number for the incoming telephone call is received. An indication that the calling device telephone number has been determined to be a source of telephone spam based on identifications by one or more users, other than a user of a mobile telephone, that the calling device telephone number is a source of telephone spam is received. A secondary alert is output to the user of the mobile telephone that is different than a default alert. The default alert is output to the user of the mobile telephone if the calling device telephone number is not determined to be a source of telephone spam.