| Area Code | 603 |
| State | New Hampshire |
| Current Time in Area Code 603 | 603> EST |
| Timezone | Eastern Standard Time |
| Regional Market Area | Northern New Hampshire Region Southern New Hampshire Region |
| Metro Area(s) | Berlin, NH Concord, NH Keene, NH Laconia, NH Lebanon, NH-VT Manchester-Nashua, NH |
| Population (2020) | 1377529 |
| Adjacent Area Codes | 207,351,802,819,873,978 |
| Belknap County |
| Carroll County |
| Cheshire County |
| Coos County |
| Grafton County |
| Hillsborough County |
| Merrimack County |
| Rockingham County |
| Strafford County |
| Sullivan County |
| Concord |
| Dover |
| Manchester |
| Nashua |
| Rochester |