Answer: phreak

AnswerCrossword Clue
PHREAKMake a call without paying, in slang
PHREAKTelephone system hacker
PHREAKMake calls without paying
PHREAKOld-style hacker
phreakperson who uses computers or other electronic devices to place long-distance telephone calls without paying toll charges
phreakto act as a phone phreak
phreakto tamper with (telephones) as a phone phreak does
phreakto hack into the phone network to get free phone calls