The North Eastern part of Nebraska including communities such as Bellevue, Lincoln, Omaha will have a new area code starting March 26, 2011. The new area code 531 will cover the existing 402 NPA. A permissive 10 digit dialing period for area code 402 was introduced on June 26, 2010 and will end on February 26, 2011. During the permissive period all local calls within area code 402 can be dialed either in the 7 or 10 digit format. Starting February 26, mandatory 10 digit dialing will be activated.
See NANPA announcement (PDF document)