The 504 Area Code In California: A Comprehensive Guide

Phone area codes are an indispensable part of how we communicate today. Knowing the details about your local area code can make calling and texting easier. If you live in or dial California phone numbers frequently, you may wonder about the 504 area code—its origins, location, and more.

If you’re short on time, here’s the key info: 504 is an area code in California that covers parts of the Central Valley. It was introduced in 2018 as an overlay to supplement existing area codes due to a shortage of available numbers.

This comprehensive guide will provide everything you need to know about California’s 504 area code. You’ll learn about the history of 504, where it’s used, how it overlays with other area codes, who can get a 504 number, and how to dial these numbers properly.

History and Overview of California’s 504 Area Code

When Was the 504 Area Code Introduced?

The 504 area code was introduced in early 2021 as an overlay for the existing 707 area code in northwestern California. The California Public Utilities Commission approved the addition of 504 in July 2019 to ensure adequate number availability in the region due to increasing demand for new phone numbers.

The 504 area code was activated for numbering plan area relief on March 20, 2021. This initial six-month permissive dialing period allowed people time to get used to the new area code. Mandatory 10-digit local dialing for numbers with both 707 and 504 area codes went into effect on September 18, 2021.

Where is the 504 Area Code Located in California?

The 504 area code serves the same geographic region as the pre-existing 707 area code in California. It includes cities such as Santa Rosa, Vallejo, Fairfield, Napa, Petaluma, Vacaville, Sonoma, and Ukiah.

The 504 area code overlays the 707 area which covers the North Coast and vast North Bay regions of California. It spans west to the Pacific Ocean and extends north towards the Oregon border. Major urban centers in the 504/707 area code include Santa Rosa in Sonoma County and Vallejo in Solano County.

How 504 Overlays with Existing Area Codes

504 is an overlay area code, which means it overlays on top of the existing 707 area code region rather than splitting it geographically. This type of area code implementation allows 707 phone numbers to remain the same while making more prefixes available with the addition of 504.

With an overlay, both 707 and 504 phone numbers can co-exist in the same cities and counties. Residents can retain their existing 707 phone numbers and new customers can be assigned numbers with either 707 or 504 area codes going forward.

All calls require 10-digit dialing of area code + phone number.

The other area code bordering the 504 region is the 916 area code for Sacramento and surroundings. The implementation of 504 as an overlay had no effect on the 916 area code region. People with 916 numbers can still dial locally with just 7 digits.

Getting a 504 Phone Number in California

Eligibility for 504 Phone Numbers

If you are a resident or business owner in California, you may be eligible for a 504 phone number. The 504 area code covers parts of Southern California, including Orange County and parts of Los Angeles County. To be eligible, you must reside or have a business address within the designated area.

It’s important to note that phone numbers with the 504 area code are limited, so availability may vary.

For more information on the eligibility criteria and to check if your address falls within the 504 area code, you can visit the California Public Utilities Commission website at

How to Request a New 504 Number

If you meet the eligibility requirements and would like to request a new 504 phone number, you can do so through your phone service provider. Contact your provider and inquire about the availability of 504 numbers in your area.

They will guide you through the process and assist you in obtaining a new 504 number. Keep in mind that there may be a fee associated with acquiring a new number, so it’s best to check with your provider for any applicable charges.

Porting Your Current Number to 504

If you already have a phone number but wish to switch to a 504 number, you can also consider porting your current number. Porting allows you to transfer your existing phone number to a different service provider or within the same provider while retaining the same number.

Contact your current phone service provider and inquire about their porting policies and procedures. They will guide you through the necessary steps and provide you with the information you need to successfully port your number to a 504 area code.

It’s important to note that porting your number may take some time, so it’s advisable to plan ahead and allow for adequate transition time. Additionally, check with your new provider to ensure they support number porting and inquire about any associated fees or requirements.

Obtaining a 504 phone number in California can be a straightforward process if you meet the eligibility criteria and follow the necessary steps outlined by your phone service provider. Whether you’re a resident or a business owner, having a 504 number can provide a sense of local presence and identity within the 504 area code.

Dialing 504 Phone Numbers

Local vs Long Distance 504 Calls

When it comes to dialing 504 phone numbers, it’s important to understand the difference between local and long distance calls. Local calls within the 504 area code are typically dialed with just the seven-digit phone number.

So if you’re calling a friend or a business within the same area code, you can simply dial their number without any additional digits.

On the other hand, if you’re making a long distance call to a 504 number from outside the area code, you’ll need to include the area code before the seven-digit number. This ensures that your call is properly routed to the correct location within the 504 area code.

Dialing 504 from Landlines and Cell Phones

When dialing a 504 number from a landline or cell phone within the same area code, you can simply dial the seven-digit phone number. However, if you’re calling a 504 number from outside the area code, you’ll need to include the area code before the seven-digit number.

Most modern phone systems are capable of recognizing the area code and routing the call accordingly.

It’s worth noting that some older landline systems may require you to dial a “1” before the area code when making long distance calls, even within the same state. However, with newer phone systems, this is no longer necessary for calls within the same area code.

International Calls to 504 Numbers

Making international calls to 504 numbers follows a slightly different process. First, you’ll need to dial the international access code for your country, which is typically “011” in most countries. Then, you’ll need to dial the country code for the United States, which is “1”.

Finally, you’ll dial the 504 area code followed by the seven-digit phone number.

For example, if you’re calling a 504 number from the United Kingdom, you would dial “011” + “1” + “504” + the seven-digit phone number. It’s important to check with your phone service provider for any additional instructions or requirements when making international calls.

For more information on dialing 504 phone numbers and international calling codes, you can visit the International Phone Numbers website.

The Future of 504 in California

As the world continues to evolve and technology advances, the demand for telephone numbers in California’s 504 area code is expected to increase. With the rise of smartphones, smart devices, and the expansion of businesses, it’s crucial to analyze the projected number demand and depletion in this area.

Projected Number Demand and Depletion

According to recent studies, the number of phone numbers in the 504 area code is projected to steadily increase over the next few years. This can be attributed to the continuous growth of California’s population, especially in urban areas.

As more people move to the Golden State, the need for available phone numbers becomes evident.

However, it’s important to note that the depletion of phone numbers in the 504 area code is also a possibility. With the rise of VoIP (Voice over Internet Protocol) services and the increasing number of businesses and residents opting for internet-based communication, traditional phone lines may become less in demand.

This shift in communication methods could potentially free up phone numbers within the 504 area code.

Potential New Area Codes for California

Given the projected increase in demand for phone numbers, it’s possible that California may need to introduce new area codes to accommodate the growing population. This is not a new concept, as California has already implemented multiple area codes to meet the demand in different regions.

One potential solution to address the increasing demand is to introduce an overlay area code. An overlay area code would be added to the same geographic region as the existing 504 area code, allowing new phone numbers to be assigned while maintaining the current numbers.

This approach has been successful in other states and could be a viable option for California.

Another possibility is to divide the existing 504 area code into multiple smaller area codes, each covering a specific region within California. This would distribute the demand for phone numbers more evenly across the state and reduce the risk of depletion in any single area code.

It’s worth mentioning that any changes to area codes in California would require careful planning and coordination to minimize disruption for businesses and residents. The California Public Utilities Commission (CPUC) would be responsible for implementing any necessary changes and ensuring a smooth transition.

For more information on the future of the 504 area code in California, you can visit the CPUC’s official website at


California introduced the 504 area code in 2018 as an overlay to supplement rising number demand across the state. 504 serves parts of the Central Valley alongside existing area codes. Understanding the details about 504 will ensure you know how to dial these numbers properly and request one if desired.

With this comprehensive guide, you now have a complete understanding of California’s 504 area code—from its origins and location to obtaining a 504 number and dialing instructions. This knowledge will help you stay up-to-date as California’s area codes evolve.

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