Help with my dog, he won't come when I call him..?

He's a Beagle, and he's a puppy. Beagles are a hound breed. They will follow their noses to distraction, and it's difficult to gain their full attention. Some will not ever be able to be trusted entirely off leash. He needs to be on a long line when he is not in a fenced area. No 5 month old puppy comes when called every time. They're just kids, and testing boundaries. Call him ONCE. If he doesn't come, reel him in with the long line. Reward for coming to you. Repeat. Don't end his fun every time he comes, either. Call him, reward, then let him go play some more most of the times you call him to you With some work, it's possible you can teach him to come reliably, but it's also possible given his breed that he won't be able to be off leash outside of a yard- ever. Seems like you did not research this breed's personality prior to bringing it home.