Well first verify their credentials and then call the cps office to make sure. You don't want random people in your house and around your child. Offer to take a drug test without them asking. Make sure your house is clean and everything is put away. You don't want them to say anything.
CPS is aware that non-custodial parents sometimes call to make trouble. If your son is healthy and happy, and there are no drugs in your home, you have nothing to worry about. These people are trained to recognize drug use - if you're not a doper, you're OK. Someone calling from another state will get them suspicious, but they have to investigate anyway.
How do you know he called?
& How about you answer the door, Don't make yourself all scetch about it,
Take a drug test if that's what they want you to do,
& If your really NOT doing drugs then your fine.
If you a, Then your dumb. & Your SOL.
Put your kid(s) First.