Fuente: Wipo "digitalization" A method and apparatus for unified overlay dialing enables simplified telephone dialing to occur within a standard overlay area and eliminates disruption dealing with area code saturation. Each three-digit area code within an overlay area is associated with a single-digit suffix, with the parent area code obtaining the suffix "0". Intra-overlay area dialing then proceeds on the basis of a seven digit number plus a one-digit suffix, rather than a full 1+10-digit number. For dialing to the parent area code from within the overlay area, the suffix may be omitted entirely, and the expiration of a suitable timing delay causes the seven digit number provided to be dialed into the original (parent) area code. This method can be implemented in connection with a telephone company central office switch, a modified custom calling service or be made accessible to individual telephone subscribers using computerized customer premises equipment. It can also be used to simplify dialing in non-overlaid situations.