Calls from a phone identified as being a source of harassing or other undesirable phone calls are blocked at a mobile positioning center (MPC). Upon request by the PSAP, a call record detail can be obtained from the MPC revealing a simulated “callback phone number”. The MPC then intercepts all future incoming calls from that simulated callback phone number and routes them to a recording that advises the harasser that the phone has been identified as a harasser and is now blocked. The recording can also advise the caller how to restore service. In a preferred embodiment, the MPC sets a timer to automatically restore service after a designated length of time.