NPA-NXX - 603-531

This is the 603-531 subcode (NPA-NXX) prefix page. Follow a prefix to find the number you are looking for. We divide our pages up to make them more user friendly to navigate!

1. Area Codes
2. 603
3. 603-531

The 603-531 subcode mainly covers Portsmouth in Rockingham county. But other numbers maybe included as well.

We have a database of information derived from the public phone records of New Hampshire state. Many of the numbers in this subcode are Cellular (Dedicated) registered to At&t Mobility. We hear they employ a large number of people in the New Hampshire office.
Recently there have been an increase in reported calls, we've had over 295223 comments across our systems for the 603-531 subcode.