← Area code 423
423-866 phone numbers
Numbers 423-866-0000 to 423-866-9999 are assigned to Comcast Ip Phone, LLC in Niota, TN. 2 of its ten thousand-number blocks are assigned to other carriers (number pooling).
Not assigned to any carrier: 423-866-2xxx, 423-866-3xxx, 423-866-4xxx, 423-866-5xxx, 423-866-7xxx, 423-866-8xxx, 423-866-9xxx — calls from these use spoofed caller IDs.
Source: North American Numbering Plan Administrator, Nov 3, 2026. Numbers can move between carriers.