Find out who called from that unknown San Mateo number using our free reverse phone lookup service. Enter the full 10-digit number (including 650 or any other US area code) to search for available caller information including name, address, phone carrier, and more.
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Got a phone call or message from a San Mateo, California phone number you don't recognize? Before you answer, call back, or reply, use our phone number lookup service to find out who's really on the other end, is it a scam, legitimate business or someone you'd rather avoid.
The total population of San Mateo, CA, is 105,661. That's thousands of potential callers you might not recognize: local business contacts, neighbors, service providers, or people from across the city.
An unknown caller could be anyone — a sales call, an old friend, someone you actually want to talk to. Without caller identification, you either ignore potentially important calls or answer ones you'd rather avoid.
Scam and spam calls continue to impact CA residents which, according to the National Do Not Call Registry Data Book, filed 287,916 complaints about unwanted calls in 2024. Of these, 161548 were robocalls, while 98127 involved live callers. The top complaint topics included imposters (27125), reducing debt (20756), medical and prescriptions (13374).
According to FTC 2024 data, CA residents reported 238,705 fraud cases in 2024, resulting in $1,678,703,608 in losses, with a median loss of $542 per victim. Given that more than 1 in 3 fraud attempts occur over the phone, verifying who is calling is critical for preventing financial losses.
If you receive fraudulent calls or suspect a scam attempt, report it to reportfraud.ftc.gov or local police department using the following contacts:
Additionally, protect your household by registering your phone numbers at donotcall.gov or by calling 1-888-382-1222 from the number you wish to register.
Have you received a call from a business but aren’t sure if it’s really them? San Mateo is primarily located in San Mateo County, which, according to U.S. Census Bureau data, includes 18,903 firms and 21,632 establishments employing 464,365 people.
| County | Percent of City | Firms | Establishments |
|---|---|---|---|
| San Mateo | 100.00% | 18903 | 21632 |
Use our service to reverse-lookup unknown California phone numbers to verify whether they actually belong to a company before answering or calling back. By cross-referencing phone numbers with local business directories, you can ensure you’re dealing with legitimate local businesses, services, contractors, or vendors—not scammers spoofing local numbers to gain your trust.
San Mateo area codes are 650. Phone numbers in California follow the following structure under the North American Numbering Plan:
Understanding the area code can help you determine if a call is local to your area. However, keep in mind that due to mobile number portability and VoIP services, the caller may be anywhere in the United States, so it’s best to search for the most recent phone number details.
ThisNumber U.S. phone directory contains name and address records for over 23 million phone numbers. Our free reverse phone lookup results may include available information on:
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