You can use the same number to call and check on a contractors License. Don't hire the first contractor who comes along. However, even on the smallest job, you must get proof that the person you are dealing with has a contractor's license in the trade for which you expect to have the work done. Get a written contract that contains all the details of the job to be performed. Deal only with licensed contractors.
Consumers have very little, if any recourse against unlicensed contractors.
All contractors are issued pocket licenses which show the type of trade for which they are licensed and the expiration date of the license. If the person says he or she is representing a contractor, but can't show you a contractors license or HIS registration, then call the contractor and find out if the person you are dealing with is authorized to act on behalf of the contractor. Get at least 3 bids and ask for references of work the contractor has completed in the local area. Contact the people provided as references by the bidding contractor and ask questions that will help you decide whether the contractor you are considering hiring will satisfy your needs. This takes time, but saves money and aggravation in the long run.