Look up any NPA-NXX to see who was assigned the prefix and where it sits.
Enter an area code and prefix to see who was assigned it, where it sits and when. It is free, with no signup.
Free & rate-limited. No signup required to try.
An NPA-NXX lookup finds who a phone prefix belongs to. NPA is the three-digit area code and NXX is the three-digit prefix after it. 1Lookup's free NPA-NXX lookup reads NANPA's public register of 198,436 assigned prefixes and shows the company it was assigned to, its place, rate center and assignment date.
- Free, no signup
- 198,436 assigned US prefixes
- NANPA file of 1 October 2026
- Exact number: free account
You can read a phone prefix in under a minute.
Split the number into three parts.
The first three digits are the area code (NPA), the next three are the prefix (NXX) and the last four are the line number.
Enter the area code and prefix.
Type six digits, such as 415 392, or paste a full ten-digit number. The lookup uses its first six digits.
Read who the prefix was assigned to.
The result shows the company, the place, the rate center, the OCN and the date NANPA assigned the prefix.
Check the exact number if the carrier matters.
A prefix names its first holder only. Pooling and porting move single numbers, so a free account runs the number itself.
Source: NANPA central office code assignments, published by North American Numbering Plan Administrator.
Need this at scale? Carrier Lookup API
A prefix names the company it was first given to. The API names the carrier of each exact number, with its line type and ported flag.
An NPA-NXX is the first six digits of a North American phone number, and NANPA assigns each one to a single company.
A North American phone number has three parts: the area code (NPA, for numbering plan area), the prefix (NXX, also called the central office code) and a four-digit line number. The N in NXX is any digit from 2 to 9 and each X is any digit, so a prefix never starts with 0 or 1. The North American Numbering Plan Administrator (NANPA) assigns each prefix to one company, the code holder, and publishes the list.
NANPA's file of 1 October 2026 lists 198,436 assigned prefixes in 368 area codes across 56 states and territories, tied to 18,449 rate centers. This tool reads that file directly, so it makes no API call and shows exactly what the register says.
A prefix tells you who was given a block of 10,000 numbers, not who serves one number today. 142,484 of the 198,436 prefixes (71.8%) are pooled, which splits the block into ten blocks of 1,000 numbers that can go to different carriers, and any single number can have been ported since. That is why the result names the code holder, and a lookup of the exact number names the carrier.
Use this page when you need the place and the first holder of a prefix: to read a number you cannot place, to see which rate center a prefix belongs to, or to check that a prefix on a list exists at all.
The carrier lookup API names the carrier of the exact number for whole lists.
When the check has to run on single numbers inside your own software or across thousands of them, the API returns the carrier, line type, OCN, LRN and rate center for 1 credit a lookup. See the carrier lookup API. To see the OCN and routing number behind one number, use our free OCN lookup. To see every prefix inside an area code, open the area code lookup. To read what each company name in a result means, see our guide to carrier names. To find the carrier of a number in any country, use our free carrier lookup.
An NPA-NXX lookup returns these fields, and each one answers a different question.
This is the real result for the prefix 415-208 as NANPA's register lists it. The first seven fields are free on this page, and a free account opens the rest for the exact number.
- Prefix415-208
- Assigned toAT&T Mobility, mobile network
- PlaceNovato, CA
- Rate centerNOVATO
- OCN6010
- Assigned onJuly 22, 2026
- Number poolingPooled in blocks of 1,000
Opens with a free trial
- Carrier of the exact numberRevealed with a free account
- Line typeMobile, landline or VoIP
- Ported statusPorted or not
- Do Not Call statusListed or not
Prefix
The area code and the prefix, the six digits the register is keyed on.
Assigned to
The company NANPA assigned the whole prefix to, with a few words on what kind of company it is. It is the first holder, not always the carrier of one number.
Place
The place the rate center resolves to. It is left blank when the rate center cannot be matched to one place.
Rate center
The geographic area the prefix is tied to in numbering records and rating, written the way they abbreviate it.
OCN
The four-character operating company number the prefix was assigned under, a code for the company's operating unit.
Assigned on
The date NANPA assigned the prefix. The file carries a date for 85,134 of 198,436 prefixes, all from 2001 on.
Number pooling
Whether the prefix is split into blocks of 1,000 numbers that can belong to different carriers.
Carrier of the exact number
The network one full number is on now, read from that number's own record, which reflects a port.
Line type
Whether the number is a mobile line, a landline or a VoIP number, which decides how it can be reached.
Ported status
Whether the number moved away from the company its prefix was assigned to.
Do Not Call status
Whether the number is on the Do Not Call list, which matters before a sales call or text.
The lookup reads the public register in three steps.
You enter an area code and a prefix.
Type six digits, or a full ten-digit number. The lookup keeps the first six digits and drops a leading 1.
We read NANPA's assignment record.
The prefix is found in NANPA's public file of assigned prefixes, so there is no live call to a carrier and no wait.
You read who holds the prefix.
The result shows the company, place, rate center, OCN, assignment date and whether the prefix is pooled. A free account adds the carrier, line type and ported status of the exact number.
An NPA-NXX lookup reads a public register, so it needs no call to a carrier.
This is the path one lookup takes. The prefix is found in a file NANPA publishes, and the place is matched from its rate center.
- You enter six digitsThe area code and the prefix, from a short code or a full number.
- The prefix is found in NANPA's fileOne row for each assigned prefix, with its holder, rate center, OCN and dates.
- The place is matchedThe rate center is matched to the place it covers, and left blank when it cannot be matched.
- You get the resultThe holder, place, rate center, OCN, date and pooling flag. The carrier of the exact number needs a free account.
A North American phone number splits into three parts, and each part has a different job.
The register is keyed on the first six digits. This is what each part is called, what it identifies and who gives it out.
| Part | Digits | Also called | What it identifies | Who assigns it |
|---|---|---|---|---|
| Area code | 3, such as 415 | NPA, or numbering plan area | A region of the numbering plan | NANPA assigns each area code |
| Prefix | 3, such as 392 | NXX, or central office code | A block of 10,000 numbers inside an area code | NANPA assigns each prefix to one company |
| Line number | 4, such as 0132 | Station number | One number in the block | The holder of the block gives it to a customer |
California holds 22,086 of the 198,436 assigned prefixes, which is 11.1% of the register.
These are the ten states with the most assigned prefixes in NANPA's file of 1 October 2026. A state with more people and more carriers needs more prefixes, and this counts prefixes, never numbers or customers.
| State | Prefixes assigned | Share of all prefixes |
|---|---|---|
| California | 22,086 | 11.1% |
| Texas | 16,086 | 8.1% |
| New York | 12,046 | 6.1% |
| Florida | 11,180 | 5.6% |
| Illinois | 8,977 | 4.5% |
| Pennsylvania | 8,256 | 4.2% |
| Ohio | 7,301 | 3.7% |
| Michigan | 6,881 | 3.5% |
| Georgia | 6,286 | 3.2% |
| New Jersey | 5,625 | 2.8% |
Source: NANPA central office code assignments, file of 1 October 2026.
71.8% of prefixes are pooled, so most prefixes are shared between carriers.
Of the 198,436 prefixes in the file, 142,484 are marked as pooled codes. A pooled prefix hands out its numbers in blocks of 1,000, so the code holder is the first holder and not always the carrier of a number inside it.
| Kind of prefix | Prefixes | Share of all prefixes | What it means for a lookup |
|---|---|---|---|
| Pooled | 142,484 | 71.8% | Blocks of 1,000 numbers can belong to other carriers |
| Whole prefix, not pooled | 55,952 | 28.2% | All 10,000 numbers were given to the code holder |
Source: NANPA central office code assignments, file of 1 October 2026.
Thousands-block pooling splits one prefix into ten blocks of 1,000 numbers.
The FCC's pooling rule is why a prefix no longer settles who holds a number. Each block is allocated separately within a rate center, and the table shows what changed.
| Unit that is assigned | Numbers in it | Holders one prefix can have |
|---|---|---|
| A whole prefix (NXX) | 10,000 | One company |
| A thousands-block of a pooled prefix | 1,000 | Up to ten companies, one for each block |
NANPA dated 11,620 prefixes in 2006 to 2010, the fewest of any period in the table, and 25,918 from 2021 to October 2026.
The file carries an assignment date for 85,134 of the 198,436 prefixes (42.9%), and its dates start in 2001. The last period is 2021 to 1 October 2026, so it is not a full five years.
| Period | Prefixes assigned | Busiest year | Prefixes that year |
|---|---|---|---|
| 2001 to 2005 | 18,822 | 2001 | 7,102 |
| 2006 to 2010 | 11,620 | 2006 | 2,822 |
| 2011 to 2015 | 13,098 | 2015 | 3,278 |
| 2016 to 2020 | 15,676 | 2020 | 4,610 |
| 2021 to October 2026 | 25,918 | 2021 | 6,649 |
Source: NANPA central office code assignments, file of 1 October 2026.
A prefix record and a number lookup answer different questions.
The register is the right source for who was given a prefix. A lookup of the exact number is the right source for who holds one number. The two disagree most often on pooled prefixes and ported numbers.
| Question | The NPA-NXX register | A lookup of the exact number |
|---|---|---|
| What does it describe? | A whole prefix of 10,000 numbers | One phone number |
| Whose name does it show? | The company the prefix was assigned to | The carrier that holds the number, from its own record |
| Does it show a port? | No, a ported number keeps its prefix | Yes, in the ported flag and the LRN |
| Does it handle pooled prefixes? | Only as a flag; 71.8% of prefixes are pooled | Yes, because it answers for the single number |
| When is it the right check? | Placing a prefix, or counting who holds prefixes | Knowing whose line one number is on |
A lookup of the exact number costs 1 credit, about $4.95 per 1,000 on Starter and $2.00 on Enterprise.
These are the monthly plans on the pricing page. The carrier, line type, OCN and routing number come back on the same lookup, every plan starts with a 7-day free trial, and the same credits pay for every other 1Lookup check.
| Plan | About per 1,000 lookups | Monthly price | Number lookups included |
|---|---|---|---|
| Starter | $4.95 | $99 | 20,000 |
| Growth | $3.52 | $299 | 85,000 |
| Professional | $3.20 | $799 | 250,000 |
| Enterprise | $2.00 | $1,999 | 1,000,000 |
You can look up the carrier of a whole list of numbers with one CSV file.
A prefix names one company for 10,000 numbers. With a 1Lookup account you upload a CSV file, pick the column that holds the numbers and download the same file back with the carrier of each number filled in. These are 7 of the columns it adds, with invented numbers.
| phone | Carrier Full Name | Line Type | LRN | OCN | State | Rate Center | Porting Status |
|---|---|---|---|---|---|---|---|
| (206) 555-0114 | T-Mobile USA, Inc. | Mobile | 2065550000 | 6529 | WA | SEATTLE | NOT_PORTED |
| (415) 555-0163 | Pacific Bell | Landline | 4155550000 | 9740 | CA | SNFC CNTRL | NOT_PORTED |
| (404) 555-0129 | Onvoy, LLC | VoIP | 4045550000 | 649C | GA | ATLANTA | PORTED |
- 1 credit a number, the same price as one API lookup.
- Up to 2 million rows in one CSV file.
- Up to 1,000 API requests a minute on every account.
The carrier lookup API returns the carrier and rate center of an exact number as JSON.
Send the number in international format (+1 and ten digits) to the phone endpoint with your API key. Each request costs 1 credit, and every account can send up to 1,000 requests a minute. The carrier name is in insights.raw_api_fields.network, the rate center in insights.raw_api_fields.ratecenter and the routing number in insights.routing.lrn.
curl -X POST https://app.1lookup.io/api/v1/phone \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"phone_number": "+12065550114"}'import requests
response = requests.post(
"https://app.1lookup.io/api/v1/phone",
headers={"Authorization": "Bearer YOUR_API_KEY"},
json={"phone_number": "+12065550114"},
)
data = response.json()["data"]
print(data["insights"]["raw_api_fields"]["ratecenter"])const response = await fetch('https://app.1lookup.io/api/v1/phone', {
method: 'POST',
headers: {
'Authorization': 'Bearer YOUR_API_KEY',
'Content-Type': 'application/json'
},
body: JSON.stringify({ phone_number: '+12065550114' })
})
const { data } = await response.json()
console.log(data.insights.raw_api_fields.ratecenter)Response
{
"success": true,
"data": {
"request": { "type": "phone", "input": "+12065550114" },
"classification": {
"line_type": "MOBILE",
"portability_status": "NOT_PORTED"
},
"insights": {
"routing": { "lrn": "2065550000", "is_ported": false },
"raw_api_fields": {
"network": "T-MOBILE USA, INC.",
"ocn": "6529",
"ratecenter": "SEATTLE",
"state": "WA"
}
},
"metadata": { "credits_used": 1, "credits_remaining": 9998 }
}
}To run the same lookup from your own software, see our carrier lookup API.
It reads the official register, not a scraped list.
Every result comes from NANPA's file of 1 October 2026, the register the numbering administrator publishes, with no API call in between.
It shows the place a prefix is tied to.
The rate center and the place it resolves to appear on every assigned prefix, and the place is left blank when it cannot be matched.
It says when a prefix is pooled.
A pooled prefix is shared between carriers in blocks of 1,000 numbers, so the result tells you when the prefix alone cannot name a carrier.
It tells an unassigned prefix from a working one.
A prefix that is not on the list is reported as not assigned, with the count of prefixes its area code does have.
Who uses this tool
Telecom teams use it to identify the holder of a number block.
Before a port request or a trunk change, the register shows which company was assigned the prefix and the OCN it was assigned under.
Fraud teams use it to place a caller's prefix.
A prefix tied to one rate center shows where a number was first assigned, which is a first check against a profile that claims another place.
Billing teams use it to read the rate center behind a prefix.
Rating and routing follow the rate center, so the register is where a rate center on an invoice is matched to a prefix.
Marketers use it to check that the prefixes on a list exist.
A US number whose prefix is not assigned cannot be a working number, so a list full of them has typos or made-up entries.
Frequently asked questions
What does NPA-NXX mean?
NPA-NXX is the first six digits of a North American phone number. NPA stands for numbering plan area, which is the area code, and NXX is the central office code, which is the three-digit prefix after it. In 415-392, the NPA is 415 and the NXX is 392.
What is the NXX in a phone number?
The NXX is the three digits that follow the area code. The N stands for any digit from 2 to 9 and each X for any digit, so a prefix never starts with 0 or 1. NANPA assigns each NXX to one company, called the code holder.
How do I look up an NPA-NXX?
Enter the area code and prefix in the lookup above, for example 415 392, or paste a full number. The result names the company the prefix was assigned to, its place, rate center, OCN and assignment date, read from NANPA's public file.
Can an NPA-NXX lookup tell me who owns a phone number?
No. It names the company that holds the prefix, not the person or business using the line. For the likely owner of a US number, use the reverse phone lookup.
Does the prefix tell me which carrier a number is on today?
Not always. The register names who the prefix was assigned to. 142,484 of 198,436 prefixes (71.8%) are pooled, so blocks of 1,000 numbers inside them can belong to other carriers, and a ported number keeps its prefix when it moves. A lookup of the exact number names the carrier it is on now.
What is a pooled prefix?
A pooled prefix is one whose 10,000 numbers are split into ten blocks of 1,000 that are assigned separately within a rate center. The FCC rule on thousands-block number pooling, 47 CFR 52.20, defines it. The blocks can go to different carriers, so one pooled prefix can have up to ten holders.
What is a rate center?
A rate center is the geographic area a prefix is tied to in numbering records and local rating, written in short forms such as SNFC CNTRL for San Francisco. NANPA's file lists one for every assigned prefix, and the tool shows the place it covers when it can be matched.
What is the difference between an initial code and a growth code?
NANPA's file marks some prefixes as initial codes, the first prefix a company received in a rate center, and others as growth codes, further prefixes for the same rate center. Of 198,436 prefixes, 44,734 are initial and 47,276 are growth, and the other 106,426 carry no code type.
Why does my prefix say it is not assigned?
Three things cause it. The digits may have a typo, the prefix may have been assigned after NANPA's file of 1 October 2026, or the area code may be one that this register does not list. A prefix that is not on the list is either still available or held back by NANPA.
Does the lookup cover Canada and the Caribbean?
The register this tool reads lists prefixes in the United States and its territories. For an area code in Canada or the Caribbean, the tool says which country the code belongs to and does not guess a holder. The free carrier lookup names the network for numbers in any country.
How many prefixes and area codes are in the register?
NANPA's file of 1 October 2026 lists 198,436 assigned prefixes in 368 area codes, tied to 18,449 rate centers and 2,954 operating company numbers. 1,064 of the prefixes are assigned but not in service yet.
What is the difference between an NPA-NXX lookup and a carrier lookup?
An NPA-NXX lookup describes a whole prefix of 10,000 numbers and reads a public register. A carrier lookup describes one phone number and reads that number's own record, which reflects ports. They answer different questions, so a free account runs the carrier lookup on the exact number.
Is this NPA-NXX lookup really free?
Yes. The prefix lookup is free to use online and rate-limited for fair access, and it needs no signup. To find the carrier, line type and ported status of the exact number, or to process numbers in bulk, sign up for a 7-day free trial, then use the API as you scale.
How much does a number lookup cost per number after a prefix lookup?
A number lookup that names the carrier of the exact number costs 1 credit in the API or a CSV upload. That is about $4.95 per 1,000 on the Starter plan, $3.52 on Growth, $3.20 on Professional and $2.00 on Enterprise. The prefix lookup on this page is free, and every plan starts with a 7-day free trial.
Is there an API that returns the carrier for a list of numbers?
Yes. The 1Lookup carrier lookup API returns the carrier, line type, OCN, routing number and rate center of each number, one at a time in real time or for whole lists from a CSV upload, starting with a 7-day free trial.
These pages answer the question that comes after an NPA-NXX lookup.
- OCN lookupThe carrier, OCN and routing number behind one full number.
- Area code lookupWhich companies hold the prefixes inside an area code.
- Carrier names in lookupsWhat each company name in a result means, with its prefixes by state.
- Number portability lookupWhether a mobile number moved to another network.
The first three digits of a US number tell you where it was assigned.
Every area code has its own page with the places it covers, the local time there, and what to do when a call from it looks spoofed. These are the codes people look up most.
- 213Los Angeles
- 646New York City
- 917New York City
- 202Washington
- 404Atlanta
- 702Las Vegas
- 786Miami
- 415San Francisco
- 206Seattle
- 954Fort Lauderdale
- 323Los Angeles
- 929New York City
Area code 213, downtown Los Angeles, also has a page for each of its 786 prefixes, with the company NANPA lists as the holder.
New area codes catch people out, because a number from one looks unfamiliar even when it is local. These are the newest working codes.
- 465New York, since Jun 2026
- 483Alabama, since Feb 2026
- 471Mississippi, since Jan 2026
- 679Michigan, since Nov 2025
- 457Louisiana, since Sep 2025
- 729Tennessee, since Sep 2025
These carrier names show up on phone lookups, and each one has a page.
A lookup often names a company you have never seen on a bill. Each page below says what the company is and where it holds numbers.
- Onvoy, LLCSupplies numbers to VoIP and app-based phone services
- Level 3 Communications, LLCLumen's business and wholesale network
- Bandwidth.com CLEC, LLCSupplies numbers to VoIP and app-based phone services
- Neutral TandemWholesale phone carrier
- New Cingular Wireless PCS, LLCMobile network
- T-Mobile USA, Inc.Mobile network
- Peerless NetworkWholesale phone carrier
- Teleport Communications America, LLCAT&T's business phone network
To see who holds America's phone numbers overall, read our study Who Hands Out America's Phone Numbers in 2026.