My boyfriend calls back anybody who calls me

From a female CFB reader

I've been dating this guy for a year and half now, and we've been good from the start but recently he's been acting weird. Anytime I talk on the phone with someone, he asks me who called and if it's someone he doesn't know, he calls the person back. I've lost a lot of friends because of him. He has also asked me to stop talking to them with the excuses they will corrupt me or they are potential threats ..I don't know what to do! I need help.