Location on iPhone

My sons iPhone is set for me to see where he’s at, when he’s out and about. I was seeing him in many different spots a couple weeks ago. I even drove right up to him. But now it shows he’s at one place always. I know he can transfer calls. But I have texted him and he answers me. I even saw a couple times that I could see him and he told me data was shut off and he turns it on and I see where he’s at. Can he do something with his phone from anther phone?