Area Code 231-637 located in NORTHPORT, LEELANAU, MI, more detail is as below. Place NPA (Numbering Plan Area) : 231 NXX (Local Number Prefix) : 637 City : NORTHPORT County : LEELANAU State : MI (Michigan) NXX Use Type : Landline NXX Intro Version : 2002-02-13 FIPS (Federal Information Processing Standards) : 26089 LATA (Local Access Transport Area) : 348 Rate Center : NORTHPORT ZIP Code Count : 0 ZIP Code Frequency : Most frequently occurring ZIP Code, although percentage is unknown. ZIP Code : 49670 Other Information NPANXX : 231637 County Population : 0 Switch CLLI (Common Language Location Identifier) : GDRQMIFOCA0 MSA CBSA (Core Based Statistical Area) : Traverse City, MI MSA CBSA Code (Core Based Statistical Area) : 45900 Time Zone : Eastern (GMT -05:00) Observes Daylight Saving Time : Yes Company : TELNET WORLDWIDE, INC. OCN (Operating Company Number) : 4632 Coverage Area Name : NORTHPORT Latitude : 45.1334 Longitude : -85.6187 ‹ previous : 231-636 next › : 231-638 Telephone Number List 231-637-0000 ~ 231-637-9999