my mom says: "I've got an app [on my smartphone] so that I can call and internet via my phone at work, so I don't use any minutes or MBs! :) "
me: "So how does your phone communicate with your work phone then? "
my mom: "via the app"
me: "without using minutes or MBs?"
my mom: "yes"

me: "So how does your phone communicate with your work phone then? "
my mom: "via the app"
me: "without using minutes or MBs?"
my mom: "yes"
etc