Area Code 240: Get a Rockville Phone Number

240 · Rockville

What is the area code for Rockville?

The area code for Rockville, Maryland is 240, with overlay code 301 sharing the same geographic footprint. The 240 area code is a North American Numbering Plan geographic code assigned in 1997, covering the Western Maryland region. It serves approximately 1,500,000 residents on the Eastern Time (ET) (UTC-5 / UTC-4 DST).

The 240 area code has 785 assigned central-office prefixes (NXX codes, the three digits after the area code) across 63 rate centers, with numbers allocated to roughly 50 carriers.

At 785 of the ~792 usable central-office prefixes, the 240 area code has about 99% of its numbering capacity assigned, and that near-exhaustion is part of why overlay code 301 was added to the region. See how 240 compares in our NXX prefix allocation analysis across 338 US area codes. (Prefix data: localcallingguide.com / NANPA, 2026.)

Where is area code 240? Location and map area

Area code 240 is located in Maryland, the United States. Its coverage area centers on Rockville and spans the Western Maryland region. If you received a call from a 240 number, the caller's number was assigned in this area — though with number porting and virtual numbers, the person may be calling from anywhere.

The 240 location sits in Eastern Time (ET), so local business hours run roughly 9 a.m.–5 p.m. ET. Neighboring Maryland area codes include 301, 410, 443.

All Rockville area codes

Rockville is served by 2 area codes across the metro area. 240 is the 1997 addition; the others were added as overlays or for surrounding suburbs.

• 240 (current page) — Overlay on the same metro, assigned 1997
• 301 — Rockville — 1947 original

Cities served by the 240 area code

The 240 area code covers 5 major cities and towns across the Western Maryland region (MD):

Businesses across Rockville and surrounding cities use 240 numbers to project local presence and lift call answer rates. Industry studies of local presence dialing consistently report answer-rate gains of 20–40% over toll-free or out-of-area numbers — a caller ID that matches the recipient's region looks familiar and gets picked up.

240 area code time zone and business hours

The 240 area code is in the Eastern Time (ET) zone (UTC-5 / UTC-4 DST). Standard business hours in 240 run 9 AM to 5 PM ET.

If you're calling into 240 from a different time zone, factor in the offset. For example, an Eastern Time business calling 240 at 9 AM ET reaches Rockville at local time — likely outside standard business hours.

History of the 240 area code

The 240 area code was introduced in 1997 when the North American Numbering Plan was first deployed. As Rockville grew and number demand increased, overlay code 301 was added to serve the same geographic region — a common solution that avoids forcing existing subscribers to change their numbers.

• 1947 301 added to serve the same region
• 1997 240 entered service

Is the 240 area code safe? Spam and scam calls

240 is a legitimate geographic area code for Rockville — it is not a scam code or a premium-rate prefix, and a call from a 240 number is most likely a genuine local caller. The risk is not the area code itself but a tactic called neighbor spoofing: scammers fake their caller ID so an unwanted call appears to come from your own area code, because people answer familiar numbers more readily.

If you get an unexpected 240 call, a few signals point to a likely scam — a pre-recorded message, urgent pressure to act now, a demand for payment by gift card or wire transfer, or anyone asking for passwords, Social Security, or account numbers. Let suspicious calls go to voicemail, never share personal information, and report fraud to the FTC at reportfraud.ftc.gov.

The FCC consumer guide on spoofing explains your rights under the Truth in Caller ID Act. A real Rockville business will leave a clear voicemail and will not pressure you.

US carriers verify caller ID with the STIR/SHAKEN framework, which flags many spoofed numbers as "Spam Likely" before they ring. DialPhone 240 numbers are registered for STIR/SHAKEN attestation, so calls from your business are verified as genuine and reach customers without a false spam label. See the DialPhone guide to VoIP security for more.

Why get a 240 area code number for your business?

Getting a 240 number gives your business three measurable advantages over a toll-free or out-of-area number:

1. Local trust signal. Customers in Rockville recognize 240 as their home area code. Caller ID matching builds immediate credibility for service businesses, sales outreach, and patient communication.
2. Higher answer rate. Calls from a familiar local area code are answered far more often than unknown or toll-free numbers — industry measurements of local presence dialing put the lift at 20–40%, which matters most for outbound sales, appointment confirmations, and time-sensitive service callbacks.
3. Targeted marketing. Businesses serving Rockville and the broader Western Maryland can advertise a local number across print, radio, billboards, and digital channels for higher conversion than a national 800 number.

For businesses in Rockville and surrounding cities, top industries that benefit from local 240 presence include Professional Services, Healthcare, and Retail. DialPhone's AI receptionist is available for every 240 number — never miss a call, even after standard business hours.

How to get a 240 area code number

Setting up a 240 business number with DialPhone takes under 10 minutes:

1. Sign up for a DialPhone plan. Choose any plan starting at $24/user/month. Free 14-day trial, no credit card required.
2. Search available 240 numbers. Filter the DialPhone number inventory by area code, city, or pattern.
3. Choose your number and configure. Assign your new 240 number to a user or team, set up call routing, voicemail, AI receptionist, and business SMS.
4. Port your existing number (optional). Already have a 240 number? Free number porting in 2 to 5 business days with zero service interruption.

New to local numbers? The complete guide to getting a local phone number covers choosing the right area code, porting an existing line, and avoiding spam flags.

240 area code overlay codes

The Western Maryland region is served by multiple overlay area codes:

Area Code	Coverage
240	Primary area code for Western Maryland, assigned 1997
301	Overlay — same geography (assigned 1947)

All overlay codes serve the same Rockville region. New subscribers may be assigned any available code; existing numbers retain their original prefix.

AI receptionist for 240 area code businesses

Every DialPhone 240 number includes optional AI receptionist coverage, available 24/7. The AI handles calls when your team is unavailable — answering common questions, booking appointments, routing urgent callers to on-call staff, and capturing voicemail with full transcription and intent tagging.

For businesses in Rockville that handle high call volume, run extended hours, or need bilingual support (especially valuable in service areas with diverse customer bases), the AI receptionist reduces voicemail backlog and improves first-call resolution.

All area codes in Maryland

Maryland has 5 active geographic area codes. The 240 area code is part of the same numbering plan as the codes listed below — calls between them are typically local within the state, depending on the carrier.

Nearby area codes

Related area codes in Maryland and the Eastern Time (ET) region:

• 301 area code — Rockville, Maryland
• 410 area code — Baltimore, Maryland
• 443 area code — Baltimore, Maryland
• 667 area code — Baltimore, Maryland
• 201 area code — Jersey City, New Jersey
• 202 area code — Washington, District of Columbia

All Maryland area codes → · Browse all US area codes →

More area codes: ← 239 Fort Myers · 248 Troy →

How this page is verified

DialPhone re-verifies every area code page every 90 days. Area code geography, timezone, and overlay data come from the official North American Numbering Plan Administration (NANPA) database. Pricing reflects the published DialPhone plan tiers — see the pricing page for current details. Number availability varies; check the DialPhone signup flow for live inventory in the 240 region.

What to know before getting a 240 number

• Number availability is finite. Popular Rockville area codes can be inventory-constrained — request specific vanity patterns early.
• Porting timing varies. Most 240 ports complete in 2-5 business days; complex multi-line legacy contracts can take 7-10.
• HIPAA tier required for healthcare. The Core $24 plan doesn't include a BAA — healthcare users need Advanced ($34) or above.