← Area code 231
231-424 phone numbers
Numbers 231-424-0000 to 231-424-9999 are assigned to Acd Telecom, Inc. (rate centre CARR, MI, NANPA abbreviation). 1 of its ten thousand-number blocks are assigned to other carriers (number pooling).
Not assigned to any carrier: 231-424-0xxx, 231-424-1xxx, 231-424-3xxx, 231-424-4xxx, 231-424-5xxx, 231-424-6xxx, 231-424-8xxx, 231-424-9xxx — calls from these use spoofed caller IDs.
Source: North American Numbering Plan Administrator, Nov 3, 2026. Numbers can move between carriers.