A "phone hacker" refers to someone skilled in breaking into other people's phones or gaining unauthorized access to information on their phones without permission. Full definition
He was also responsible for bringing the convicted phone hacker Glenn Mulcaire to the paper. (theguardian.com)
So easy, in fact, that this mobile phone hacker's guide can present (myintimcity.com)
They can be located anywhere or in anything, under such deep cover that not even a News International phone hacker could unearth them. (independent.co.uk)