About this number
(312) 256 is a landline based telephone number operated by Allegiance Telecom, Inc. - Il and is located in zip code 60603 in the city of Chicago, Illinois, which is in Cook County, and is in the Midwest. It has a Number Planning Area (NPA - also known as an Area Code) of 312 and Network Numbering Exchange (NXX - also known as a prefix) of 256. It has an Operating Company Number (OCN) of 8950. A Common Language Location Identifier (CLLI) of CHCHILLEDS0. As well as a Local access and transport area (LATA) of 358. Zip code 60603 has a population of 493 as of the 2010 census.