Someone has a pretty poor taste in jokes if it is. Those things certainly act real.

[He frowns, crossing to the window and leans against the wall at an angle that lets him see outside.]

This phone works. [He reaches into a pocket on his belt and pulls out the device.] It doesn't make sense that yours wouldn't.

[Steve is calling on his very limited knowledge of how phones work here. He has absolutely no idea about JARVIS though. He knows Tony talks to him and that he's not a real person.] Isn't he... an app on your phone?