I wouldn't use a phone in my own bathroom.
Ah, but now put a deadbolt on the bathroom door and you have a place to go when a 17 year old meth addict breaks into your house at night. And hey, if theres a phone, you can call the cops, too.
Or, if you are like me, with older parents, you put one in their bathroom so they can call for help when they have fallen and can't get up.