My friend keeps getting prank calls. how can they figure out who it is?

Question

they know everthing to

when they went to the movies and with who

her mothers nick name

they also prank call my other friend

any way to find out who it is

its realy scaring her

Answer 1

Call the phone company and ask them to do a trace on the last number that called due to harrasment the next time they call.  Then call the police.

Answer 2

you can report them if they call often, you know. They're harassing her.

Answer 3

The Phone Company Can Trace Down The Number And They Can Be Arrested For Harrasment.