Sure. ( it's not the first time he's met someone who had no idea what the hell a smart phone was. but given how much people rely on them during his era, and how basic and old these are - it's still weird as hell. but he reaches out for her phone, taking it in hand to start navigating to the contacts page. )

So, these things go off of usernames. Right? Stark's is just "T". ( which jason is pulling up from the contact list. ) So you'd just go here, and either press the call icon, or the text one. I'd stick with text. It pulls up a little keyboard, which you use to type out your message, then send it on.