Question about my child being on his father’s insurance

My son’s father is supposed to carry his auto insurance. He claimed my son was insured, but my son had to keep asking for proof of insurance. His father finally sent a picture of the insurance card, but just the father and wife are listed. My son just called the insurance agent and agent stated my son is not listed on the insurance. If my son were to get in an accident and give the insurance information he has the other driver, what will happen? Thank you in advance.