My Phones Isn’t Connected To My Phone Anymore

My Carrier Explained To Me That I Needed To Get In Contact With Apple Because My Phone Isn’t Connected To My Iphone Anymore. I’ve Had This Phone Number For Years Along With Phone. And It’s Been Paid Off For 2 Years Now And All Of A Sudden When My Husband Calls My Phone, It’s Like It’s Calling My Son Phone. But When My Son Call My Phone It Tried To Connect Him To His Carrier.