Makes it possible for customers to initiate the process of identifying harassing or obscene telephone callers.
To initiate call trace:
Hang up the phone after receiving the harassing call,
Pick up the receiver and listen for dial tone, then
Press *57 (touchtone telephones) or dial 1157 (rotary dial telephones).

Customers are notified by a prerecorded voice announcement if the trace is successful and the number of the calling party will be recorded in the telephone company office, and held until you call them or your local law enforcement agency.
The Telephone Company will release the detail information only to proper authorities.
This feature works even when the calling party blocks Calling Number Delivery but it is not available if the call is placed from an area that does not provide the calling number delivery.
If it is a threatening situation, the customer should contact their local police or sheriff's office immediately.