It is almost impossible to determine what insurance company you are dealing with by the prefix or any part of the policy number. Often times policy numbers are only made for convenience sake only. For instance, personal auto policies sometimes begin with the letters PA for personal auto and homeowners policies start with HO. This is most often when you are dealing with smaller regional insurance companies. Large national companies may be made up with nothing but numbers. The policy numbers are generally random only. There are no regulations or laws that make insurance companies use certain numbers to make up policy numbers.