>>46536188It's a sidequest that they never really explain very well. You find a lost xtranceiver and try to get in contact with the owner to return it, but they only want to call when you're in a secluded enough area. So you've got to run around Unova looking for the single tiles that are considered out of the way enough her them to get more calls and progress the plotline further.
The issue being that the game never actually tells you what the hell triggers the phone calls, so even if you stumble upon one or two, most people will assume it was just RNG and not because they found one of the spots. Some of the spots, like pic related, are pretty easy to find if you know you're looking for them (which you don't), while others are on a seemingly random tile in an open area. Very few people have gotten far enough in the quest to see either of these characters unless they had a guide explaining this side quest.