The 858 area code serves the northern part of the city of San Diego, California, including La Jolla, Rancho Bernardo, and Mira Mesa. Created in 1999, 858 shares the San Diego metropolitan area with the 619 code. If an 858 number has appeared on your caller ID, this guide explains where it comes from, how to dial it, and how to stay safe from spoofed calls.
Quick Summary: Area Code 858 at a Glance
| Detail | Information |
|---|---|
| Area Code | 858 |
| State | California (CA) |
| Major Cities | San Diego (La Jolla, Rancho Bernardo, Mira Mesa) |
| Time Zone | Pacific Time (PT) |
| Country Code | +1 (USA) |
| Overlay Codes | 619 (shared San Diego region) |
Geographic Coverage & Major Cities
Area code 858 covers the northern neighborhoods of the city of San Diego and adjacent communities in San Diego County. It shares the metro area with 619 — the boundary between the two codes was eliminated, so they now function as a combined overlay.
Neighborhoods and communities served by the 858 area code include:
- La Jolla and University City — coastal and university neighborhoods, home to UC San Diego
- Mira Mesa, Kearny Mesa, and Clairemont — central San Diego districts
- Rancho Bernardo and Carmel Valley — northern San Diego communities
- Sorrento Valley — a major biotech and technology employment hub
Because it covers San Diego’s tech, biotech, and university corridors, an 858 number carries a strong professional San Diego identity.
A Brief History of Area Code 858
Area code 858 was created in 1999, split from 619 to serve the northern part of the city of San Diego. In 2019, the boundary between 619 and 858 was eliminated, so the two codes now operate as a single overlay across the San Diego metro area, with mandatory 10-digit dialing. New numbers in the region may be assigned either code.
Time Zone & Best Time to Call
Numbers in the 858 area code use Pacific Time (PT). The region observes Daylight Saving Time, shifting from PST (UTC−8) to PDT (UTC−7) between March and November each year.
How to Dial Phone Numbers in Area Code 858
Because 858 shares the San Diego region with the 619 overlay, the area requires 10-digit dialing on every call.
Calling within the United States or Canada
- 10-digit dialing: Always include the area code — 858-XXX-XXXX.
- 11-digit dialing: You can also dial 1-858-XXX-XXXX; the leading 1 is the NANP country code.
Calling from outside the United States
- Format: [exit code] + 1 + 858 + XXX + XXXX
- From the UK, Europe, or most of Asia/Africa: 00 1 858 XXX XXXX
- From any mobile phone worldwide: +1 858 XXX XXXX
Is Area Code 858 a Scam? Safety & Protection Tips
Area code 858 is a legitimate San Diego area code — a call from it is not fraudulent by default. However, scammers frequently spoof the code so their calls appear to come from a trusted local San Diego number. Neighbor spoofing, which mimics your own number’s first six digits, is especially common.
Common scam tactics linked to this region
| Scam type | What to watch for |
|---|---|
| Tech & biotech job scams | Fake job offers requesting fees or personal information |
| Government impersonation | Callers posing as the IRS or SSA threatening legal action |
| Student & tuition scams | Calls about “unpaid tuition” targeting university communities |
| Bank & card fraud alerts | Claims of “suspicious activity” seeking your account details |
How to report, block, and look up 858 callers
- Never share personal or financial details with an unexpected caller, however urgent they sound.
- Block the number using your phone’s built-in call-blocking feature or a reputable call-screening app.
- Look up the number with a trusted reverse phone lookup before returning any call.
- Report it to the FTC at reportfraud.ftc.gov and register at DoNotCall.gov.
Nearby & Related Area Codes in California
Area code 858 shares and borders several other Southern California codes:
- 619 — the code that shares the San Diego metro area with 858 (see our 619 area code guide)
- 760 & 442 — northern San Diego County and the deserts (see our 760 area code guide)
- 951 — Riverside and the western Inland Empire
- 949 — southern Orange County to the north
Explore more codes across the state on our California area codes hub, or browse every prefix in our US area codes directory.
↑ See the complete list of All US Area Codes by State – every area code across all 50 states in one directory.
Explore Neighboring States
Researching area codes just across the state line? Start with these codes in the states that border California:
Frequently Asked Questions About Area Code 858
Where is the 858 area code located?
Area code 858 covers the northern part of the city of San Diego, California, including La Jolla, Mira Mesa, Kearny Mesa, and Rancho Bernardo. It operates on Pacific Time and shares the metro area with 619.
Is 858 a landline or cell phone area code?
Both. Area code 858 serves landlines, mobile phones, and VoIP numbers throughout northern San Diego.
What is the difference between 619 and 858?
They now cover the same San Diego region. Historically 858 served the northern communities, but since the boundary was eliminated in 2019, new numbers may be assigned either code.
Should I answer a call from an unknown 858 number?
If you are not expecting the call, let it go to voicemail. Legitimate callers leave a message, while spoofed or robocall numbers usually will not. Verify any unfamiliar number with a reverse lookup before calling back.
Related 858 Guides
- Is a 858 call safe? Read Is area code 858 a scam? Spam & safety guide.
- Local coverage: see the San Diego area code guide.
- Worried about spam or robocalls? Browse our Scam Alerts directory.