We've all had gobblers coming in right to us.  Only to have them "Hang Up", just out of range.  They stand out there strutting, but they won't come any closer.

As hunters we try to bring tom turkeys to our hen calls, and decoys that do not act like turkeys. 
Gobblers often respond to the call and come into view of our decoys.  However that's when those big ol toms "Hang Up" and start strutting, waiting for the HEN to come to him. We call it "hanging up" but in nature it is a "genetic response" meaning he waits for the hen to come show her receptiveness and come to him as nature intended.  This behavior is embedded in their genes.

Until now, about all you could do was sit tight, call to him and hope he's "hot" enough that he will come in to you. A lot of turkeys are shot that way, but sometimes you need a little more persuasion, motivation or a reason to get him in for the shot.