Mill Valley, CA — rate center
- State
- California
- Active prefixes
- 23
- Carriers
- 11
- Pooled prefixes
- 18
- LATA
- 722
- Metro area
- San Francisco-Oakland-Fremont, CA MSA
The Mill Valley rate center (California) anchors 23 active prefixes under area codes 415, 628. Rate centers, not city limits, are what phone numbers are legally tied to.
The rate center currently carries 23 working prefixes across 11 carriers. 18 prefixes participate in thousands-block pooling, so blocks of 1,000 numbers are shared between carriers.
The rate center belongs to the San Francisco-Oakland-Fremont, CA Metropolitan Statistical Area. Routing-wise it sits in LATA 722.
Multiple area codes over one rate center (415/628) is the overlay pattern: same geography, different first three digits.
A Mill Valley prefix on caller ID is a starting point, not proof of origin — numbers travel with their owners and displays can be spoofed. Use official callback numbers for anything sensitive.
Prefixes anchored to Mill Valley
| Prefix | Code holder | Pooled |
|---|---|---|
| 415-322 | BANDWIDTH.COM CLEC, LLC - CA | Yes |
| 415-326 | BANDWIDTH.COM CLEC, LLC - CA | Yes |
| 415-360 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | Yes |
| 415-380 | PACIFIC BELL | No |
| 415-381 | PACIFIC BELL | No |
| 415-383 | PACIFIC BELL | No |
| 415-384 | PACIFIC BELL | Yes |
| 415-388 | PACIFIC BELL | No |
| 415-389 | PACIFIC BELL | No |
| 415-569 | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | Yes |
| 415-634 | ONVOY, LLC - CA | Yes |
| 415-843 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | Yes |
| 415-877 | METROPCS, INC. | Yes |
| 415-879 | METROPCS, INC. | Yes |
| 415-888 | COMCAST PHONE OF CALIFORNIA, LLC | Yes |
| 415-968 | LEVEL 3 COMMUNICATIONS, LLC - CA | Yes |
FAQ
What area code is Mill Valley, CA?
Mill Valley is served by 2 area codes — 415, 628 — which overlay the same territory.
How many prefixes does Mill Valley have?
23 active NXX prefixes are anchored to this rate center in NANPA records, held by 11 carriers.
Is a call from a Mill Valley prefix really from Mill Valley?
Not necessarily. The prefix marks where the number block was issued; porting, VoIP and spoofing all detach calls from that geography.