can people steal your phone number through DSL?

Question

OK, my parents have DSL and they are getting phone calls from people claiming to have gotten it though e-mail or talking to them in one form or another. they actually ask for people by name so we think they found some information through a hack or something. no one in their house-hold told anyone this info.

so, is it possible for them to steal phone information though the DSL hook-up?
if so is it a common occurence?

Answer 1

Yes I guess so. Hackers get into Kennedy Space Center and other high security areas - why not your PC?

Answer 2

It is more likely they got the phone number from the phone book.