603-331 phone numbers

Numbers 603-331-0000 to 603-331-9999 are assigned to Level 3 Communications, LLC in Colebrook, NH. 6 of its ten thousand-number blocks are assigned to other carriers (number pooling).

Not assigned to any carrier: 603-331-7xxx, 603-331-8xxx, 603-331-9xxx — calls from these use spoofed caller IDs.

Source: North American Numbering Plan Administrator, Nov 3, 2026. Numbers can move between carriers.

Reported numbers in 603-331