Can a mobile phone be hacked when it is off?

There are two types of phone hacking: hacking into
a live conversation or into someone’s voicemail, and hacking into data stored on one’s smart-phone. Just as the majority of abductions are carried out by a member of the abductee’s family—unless you go by code name POTUS or are Hugh Grant—the person most likely to hack into your live conversation or voicemail will be someone that you know who has an axe to grind.