← Area code 231
231-581 phone numbers
Numbers 231-581-0000 to 231-581-9999 are assigned to Charter Ip Enabled Services, LLC in Alba, MI.
Not assigned to any carrier: 231-581-1xxx, 231-581-2xxx, 231-581-3xxx, 231-581-4xxx, 231-581-5xxx, 231-581-6xxx, 231-581-7xxx, 231-581-8xxx, 231-581-9xxx — calls from these use spoofed caller IDs.
Source: North American Numbering Plan Administrator, Nov 3, 2026. Numbers can move between carriers.