← Area code 603
603-975 phone numbers
Numbers 603-975-0000 to 603-975-9999 are assigned to Comcast Ip Phone, LLC (rate centre BOSCAWEN, NH, NANPA abbreviation). 1 of its ten thousand-number blocks are assigned to other carriers (number pooling).
Not assigned to any carrier: 603-975-1xxx, 603-975-2xxx, 603-975-3xxx, 603-975-4xxx, 603-975-5xxx, 603-975-6xxx, 603-975-8xxx, 603-975-9xxx — calls from these use spoofed caller IDs.
Source: North American Numbering Plan Administrator, Nov 3, 2026. Numbers can move between carriers.