603-855 phone numbers

Numbers 603-855-0000 to 603-855-9999 are assigned to Idt America, Corp. in Alton, NH. 2 of its ten thousand-number blocks are assigned to other carriers (number pooling).

Not assigned to any carrier: 603-855-0xxx, 603-855-1xxx, 603-855-3xxx, 603-855-4xxx, 603-855-6xxx, 603-855-7xxx, 603-855-9xxx — calls from these use spoofed caller IDs.

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

Reported numbers in 603-855