A plan for the allocation of unique 10-digit address numbers. The numbers consists of a 3-digit area (numbering plan area) code, a 3-digit office code, and a 4-digit line number. The plan also extends to format variations (e.g., 3-digit and 7-digit address,) prefixes (e.g., 1, 0, 01, and 011,) and special code applications (e.g., service access codes. )