Area code
443
443 is a United States area code. Under the North American Numbering Plan it belongs to Maryland, which has 6 area codes in total.
Validate a number in 443
Paste a full number and the tool checks it against the numbering plan. It returns the standard formats, the line type the plan assigns and the area code region.
Digits with or without punctuation work. Numbers outside the US are read with the +country code.
Area code 443 at a glance
NANPA lists 785 central office codes (prefixes) in use in area code 443, held by 25 holders across 81 rate centers.
| Fact | Value |
|---|---|
| In service since | 1997-06-01 |
| Time zone | Eastern (E) |
| Assigned overlays | 410 (1991-10-06), 667 (2012-03-24) |
| Prefixes in use | 785 |
| Pooled prefixes | 701 (89%) |
| Rate centers | 81 |
| Companies holding prefixes | 25 |
| Assignment dates on file | 2001-01-10 to 2023-11-21 (299 prefixes) |
| ZIP codes in its places | 110 |
Rate centers in area code 443
| Rate center | Prefixes | Share |
|---|---|---|
| BALTIMORE | 185 | 24% |
| ANNAPOLIS | 39 | 5% |
| TOWSON | 33 | 4% |
| COLUMBIA | 31 | 4% |
| GLENBURNIE | 26 | 3% |
| CATONSVL | 22 | 3% |
| PIKESVILLE | 21 | 3% |
| SALISBURY | 20 | 3% |
| 73 other rate centers | 408 | 52% |
Who holds the prefixes in 443
Paetec Itel holds the most prefixes, 153 (19%). 89% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| Paetec Itel | 153 | 19% |
| Verizon Wireless | 121 | 15% |
| Omnipoint Communications Cap Operations | 94 | 12% |
| New Cingular Wireless PCS | 71 | 9% |
| Level 3 Communications | 69 | 9% |
| Verizon Maryland | 55 | 7% |
| 19 other carriers | 222 | 28% |
A prefix holder is the company a code was assigned to, not necessarily a number's current carrier, because numbers can be ported to another company. Find which carrier a number is on, or browse the prefix holders.
History of area code 443
- 1991-10-06 Area code 410, named as the parent of 443 in the NANPA report, was in service.
- 1997-06-01 Area code 443 went into service.
- 2012-03-24 Area code 667 went into service as an overlay in the same area as 443.
Area codes nearest to 443
Distance is measured between the centers of the ZIP code places each area code serves, so it is a rough guide.
Overlay codes in the same area
ZIP codes in area code 443
110 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Baltimore, MD | 42 |
| Annapolis, MD | 8 |
| Towson, MD | 5 |
A ZIP code and an area code are unrelated systems. A ZIP code can sit in more than one area code, and an area code spans many ZIP codes.
Complaints on file for 443 numbers
4,476 FCC complaints are on file for 3,050 numbers in 443, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 154 |
| 2024 | 183 |
| 2025 | 162 |
Other area codes in Maryland
Maryland is one state with 6 area codes in the NANPA table. 443 is one of them.
Next to 443 in the numbering table
These are the codes just before and after 443 when all are sorted by number. They are neighbours on the list, not necessarily on the map.
What the area code does and does not tell you
A number that starts with 443 was first assigned in Maryland. That is a fact about where the number began, and it is a useful hint when you check a form entry, for example a billing address in Maryland next to a 443 phone number.
It does not show where the person is today. A number stays with its owner after a move or a change of provider (number portability), and mobile numbers travel with the handset. The area code also cannot tell you whether the line is active, who the carrier is, or whether the number is mobile or fixed: the plan shares those ranges. Read more about the area code, the numbering plan and line type.
Check numbers in bulk with the API
| Product | Credits | Docs |
|---|---|---|
| Phone Numbering-Plan Validation | 1 credit per valid number | API docs |
| Phone Intelligence (carrier and line status) | 1 credit per check (invalid numbers outside the US and Canada are free) | Product page |
Questions about area code 443
Where is area code 443?
NANPA assigns area code 443 to Maryland, United States.
In which state does area code 443 sit?
Maryland. 443 is one of 6 area codes the NANPA table assigns to the state.
Which places does area code 443 cover?
The places with the most ZIP codes among the rate centers in 443 are Baltimore, MD, Annapolis, MD and Towson, MD. The rate center list on this page shows all of them.
Who owns area code 443?
NANPA assigns area codes. Within 443, Paetec Itel holds the most prefixes, 153 prefixes or 19%.
Which time zone does 443 use?
The NANPA NPA report lists the time zone for 443 as Eastern (E).
What year did 443 enter service?
The NANPA NPA report gives an in-service date of 1997-06-01, so 443 has been in use since 1997.
Does area code 443 have an overlay?
Yes. 410 (in service 1991-10-06) and 667 (in service 2012-03-24) share the same area with 443, so numbers from all of them are local to each other.
Which area codes are nearest to 443?
The area codes closest to 443, measured between the centers of the ZIP code places they serve, are 301 (about 44 miles), 302 (about 50 miles), 571 (about 59 miles), 703 (about 59 miles) and 223 (about 71 miles).
How many prefixes does area code 443 have?
NANPA's report dated 2026-10-17 lists 785 prefixes in service in 443, spread over 81 rate centers and 25 holders.
Are there complaints about 443 numbers?
The FCC data on file has 4,476 complaints for 3,050 numbers in 443. They are unverified consumer reports. A number with no complaints on file is not proven safe.
Area code assignments: North American Numbering Plan Administrator NPA report, file dated 10/17/2026, retrieved 2026-10-17. Source file. New codes are assigned several times a year. Prefixes, rate centers, holders, time zone, in-service date and overlays: NANPA central office code report dated 2026-10-17 and NPA report dated 2026-10-18. Complaints: FCC consumer complaints open data, fetched 2026-10-17. ZIP code places: Postal code places and coordinates: GeoNames (geonames.org), licensed CC BY 4.0.