Many organizations haveprivate branch exchange systems which permit dialing the access digit(s) for an outside line (usually 9 or 8),a "1" and finally the local area code and xxx xxxx in areas without overlays. This "feature" is unintentionally helpful for employees who reside in one area code and work in an area code with one,two,or three adjacent area codes. "1+" dialing to any area code by an employee can be done quickly,with all exceptions processed by the private branch exchange and passed onto thepublic switched telephone network.Open and closed dialing plans should not be confused with open and closed numbering plans. A closed numbering plan,such as found in North America,features fixed length area codes and local numbers. An open numbering plan,as found in assorted countries that have not yet standardized,features variance in length of area code or local number,or both. Closed dialing plans are rare where numbering plans are open. Closed dialing plans