Cities in area code 857
857 numbers are anchored to 20 rate centers across Massachusetts. Each row shows how many active prefixes the locality holds — a direct measure of its numbering footprint.
Boston, Cambridge, Brookline, Roxbury, Newton, Quincy, Dorchester and Brighton hold the largest prefix inventories; and 11 smaller communities down to single-prefix localities. Each locality below links to its rate-center page with the full prefix list.
Metropolitan coverage: 20 rate centers belong to FCC top-100 metro areas.
Overlap note: 20 localities are shared with other area codes, so a neighbor's number may differ in its first three digits.
Clock-wise the coverage is Eastern.
A caller's real location can differ: numbers port between carriers and follow their owners when they move. Use the prefix tables to see where a specific number block was issued.
| Locality (rate center) | Active prefixes | Metro area | All codes serving it |
|---|---|---|---|
| Boston | 150 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Cambridge | 27 | Boston-Cambridge-Newton, MA-NH | 508, 617, 857 |
| Brookline | 26 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Roxbury | 20 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Newton | 18 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Quincy | 14 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Dorchester | 13 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Brighton | 13 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Charlestown | 10 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Jamaica Plain | 9 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Somerville | 8 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| East Boston | 7 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Belmont | 7 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Winthrop | 6 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Watertown | 6 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| South Boston | 6 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Hyde Park | 5 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Milton | 4 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Chelsea | 4 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
| Everett | 4 | Boston-Cambridge-Newton, MA-NH | 617, 857 |
FAQ
What is the biggest city in area code 857?
Boston holds the most active prefixes (150), making it the code's largest numbering locality.
How many places does 857 cover?
20 rate centers in Massachusetts hold active 857 prefixes, from Boston down to communities with a single prefix.
Does a 857 number guarantee the caller lives in one of these places?
No — the tables show where number blocks were issued. Porting and VoIP let people keep or acquire numbers anywhere.