Delta Airlines is one of the most popular airlines in the world. They offer great service and a variety of flights to choose from. Recently, Delta Airlines changed their flight change number policy. Previously, you could change your flight at any time without penalty. The new policy is that you must call Delta Airlines 48 hours before your original flight to make a change, and if the original flight is not available, the new flight must be within two hours of your original departure time. This change was made to improve customer service.