You didn't say how old your pup is, but it seems you have some undoing to do. It's important that your pup ALWAYS come when called but it sounds like he has already learned that he doesn't have to. (after the potty is conquered this is your next task) I would suggest that you incorporate always going out on a leash first (whether it is play or potty) - every trip out the door starts on leash - and waiting till potty is over to play. I agree with the above note to wait until about 20 - 30 minutes after food (don't take your eyes off him) then get some activity like a quick jog on the leash while encouraging him to go. After a little burst of activity, if he is disinterested in potty (and only want to play or sniff) you may need to simply stop (ideally where you want him to go) and stand still, just letting him walk in circles around you while you encourage him to potty - be consistent with your command and don't get into the play mode until he goes. So 2 things here - make sure he will need to go (he has just eaten and has about 30 minutes) and be consistent that no play happens until he goes. Good luck!