my girlfriend had this working about 7 years ago, in error i might add!
we were at uni and her computer kept turning on randomly, sometimes at night sometimes early morning. we eventually figured out she had her modem plugged into the telephone socket (for dial up internet) but whenever someone rang the telephone number for her room the pc switched on!
this was with old hardware, at least 10 years old, and it may have even been faulty hardware as i didnt think it was even possible till we tried it for ourselves and it worked!