Depends what you mean by hack.
I'll need to go to tools/settings/ etc and adjust with the configuration of the device.
The system said this query is now "open to all experts".
Just to let you know I'm happy to work with you on this unless it's not your bag.
I don't have her password. She'd give it to me and trust me to use it to make a call, as per my reason for wanting to use her phone. I wouldn't naturally say the actual reason: to adjust her mobile so her boyfriend can access her messages. (Though this is morally repugnant, I'd like to know the legal situation.)
So for clarity's sake:
If she does not reveal the password ***** me (ie she inputs it herself) before letting me use her phone, during which time I access the settings to make subsequent accessing messages (somehow) possible, then that presumably is hacking. Or not?
On the other hand... If she reveals her password, and that is used to access her phone, then that is not computer hacking and is not deemed as an offence (unless she sues under an obscure arguable point in law.)
Now what about legislation that companies have to comply with in relation to data protection. There I believe an employer can't monitor private communications unless the employee has given explicit permission. Would this apply people? I.e you can't access data on another's phone unless they give permission?