508-603 phone numbers

Numbers 508-603-0000 to 508-603-9999 are assigned to Level 3 Communications, LLC in Upton, MA. 7 of its ten thousand-number blocks are assigned to other carriers (number pooling).

Not assigned to any carrier: 508-603-3xxx — calls from these use spoofed caller IDs.

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

Reported numbers in 508-603