Jon had expected his grandfather to appear out of thin air. It didn't happen, however. Instead, he suddenly felt compelled to reach into his pocket.
He put the stone in his other hand and then got out what was inside his pocket... his cell phone. A perfectly normal cell phone, just as it was before, but by some instinct Jon opened it up and looked at his contact list. "Grandpa" had somehow been added.
It made complete sense. His grandfather probably wasn't in range of the stone. So how could Jon talk to him? Simple: by magically knowing his phone number. Jon noticed the phone number was overseas--of course it would be--but dialed it anyway.
He held the phone to his ear and someone answered on the other end....