← Area code 231
231-534 phone numbers
Numbers 231-534-0000 to 231-534-9999 are assigned to AT&T - Local (rate centre TRAVERSECY, MI, NANPA abbreviation). 9 of its ten thousand-number blocks are assigned to other carriers (number pooling).
Source: North American Numbering Plan Administrator, Nov 3, 2026. Numbers can move between carriers.