Any basic phone that you can only use to make calls and send texts: a phone that isn't a smartphone.
A: "My phone died yesterday, so I'm getting a new one."
B: "Sweet, are you getting the new iPhone?"
A: "Naw man, just aPhone."
Used like alone time but means alone time with your phone.
"Hey man, can you put your phone down for a minute and talk to me?"
"Nah, I need some aphone time right now."