NPA-NXX lookup: rate center, state and original carrier for any US prefix
An NPA-NXX lookup reads the first six digits of a North American number, the area code (NPA) and the prefix (NXX), and returns what NANPA's records hold for it: the rate center, state, LATA and the carrier the prefix or its 1,000-number block was assigned to. Numbers port between carriers, so that is the original carrier, not today's.
Sample result
Prefix 415-555 in California has no assignment in the NANPA files.
- NPA-NXX
- 415-555
- State
- CA
- Thousands block
- 0
What this means for you
An assigned prefix shows its rate center and original carrier; this one has no record.
- Rate center, state and LATA for a US prefix
- Carrier first given the prefix or block
- Reads the 1,000-number block from a full number
- Bulk mode for lists and CSV files
- NANPA
- Rate center
- LATA
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
How do I look up an NPA-NXX?
- Type an NPA-NXX such as 212-555, or paste whole phone numbers, one per line. A CSV works too; the phone column is found automatically.
- Press Look up NPA-NXX. One entry shows the full record; a list shows a table.
- For a full number, the tool also reads the thousands digit and shows who that 1,000-number block was assigned to, which can differ from the prefix holder.
- Download the list with state, rate center, LATA, original carrier and OCN columns added.
Example
- You enter
- The number
(415) 555-0132. - You get
- NPA 415, NXX 555, thousands block 0, state CA, and no assignment for prefix 415-555 in the NANPA files, so there is no rate center or original carrier to show.
- Limits
- Uploaded files can be up to 25 MB; there is no cap on the number of rows, and it all runs in your browser.
What does NPA-NXX mean?
NPA-NXX is the first six digits of a North American phone number. The NPA (numbering plan area) is the three-digit area code and the NXX is the three-digit central office code, or prefix, that follows it. In 212-555-0147, the NPA is 212 and the NXX is 555. The N stands for a digit from 2 to 9 and X for any digit, which is why no area code or prefix starts with 0 or 1.
Each NPA-NXX is assigned to one carrier for one rate center, the local exchange area that decides how calls to it are rated. That makes the prefix a reliable clue to where a number was issued and by whom, but only to that: the area code time zone tool covers the area code level, and this tool goes one level down.
Where does the NPA-NXX data come from?
From the North American Numbering Plan Administrator's public files. NANPA publishes the central office code assignment records for the US and its territories, with the state, rate center, assigned carrier and OCN (operating company number) for every prefix, and the thousands-block reports for prefixes that are pooled. The date of the files this page uses is shown under every result.
Canada isn't in these files. Canadian prefixes are administered by the Canadian Numbering Administrator, so a Canadian number here shows its area code's province but no prefix record.
Does an NPA-NXX lookup show the current carrier?
No. It shows the carrier the numbers were first assigned to. Since local number portability, a subscriber can keep the number and move it to another carrier, and the FCC's guide to keeping your number when you switch covers the rules. A number in a Verizon block may now be on T-Mobile, a cable company or a VoIP app, and the prefix data can't see it.
Today's carrier lives in the number portability database and carrier lookup services that query it, which is what the phone carrier lookup guide explains. Treat the result here as history: useful for where a number was issued, not for routing or line type.
What is number pooling, and why does the block matter?
Number pooling splits a 10,000-number prefix into ten 1,000-number blocks that can go to different carriers. NANPA's thousands-block data lists who each block went to: 212-555-1XXX might belong to one carrier and 212-555-2XXX to another. When you enter a full number, this tool reads the thousands digit and reports that block's carrier rather than the prefix holder's.
Blocks marked retained stay with the prefix holder; blocks still in the pool aren't assigned to anyone, so a number in one of those wasn't issued from that block at all.
NPA-NXX lookup or carrier lookup: which do I need?
| NPA-NXX lookup (this tool) | Live carrier lookup | |
|---|---|---|
| Rate center, state, LATA | Yes | Usually |
| Carrier | The original assignee | The current carrier, after porting |
| Mobile or landline in the US | No | Yes |
| Cost | Free | Per lookup |
| Works offline from public files | Yes | No, queries live databases |
Who uses this tool, and for what?
- SMS and call teams
- Group a lead list by state and rate center before a campaign, so local-presence numbers and send windows match where numbers were issued.
- Telecom and VoIP admins
- Check which rate center and LATA a prefix sits in before ordering or porting numbers in that area.
- Fraud and risk teams
- See where a number was first issued and whether its prefix belongs to a wireless carrier or a VoIP wholesaler, as one signal among several.
- Data teams
- Add rate center, state and OCN columns to a CRM export in one pass, in the browser.
What can’t this tool tell you?
- The carrier is the one NANPA assigned the prefix or block to. Ported numbers keep their digits, so today's carrier may differ.
- It can't tell whether a number is in service or who uses it; a prefix record says nothing about one line.
- US and territories only. Canadian prefixes come from the Canadian Numbering Administrator and aren't in NANPA's files.
- Mobiles and landlines share prefixes in the US, so the prefix doesn't give the line type.
- The data is a snapshot of NANPA's files on the date shown, refreshed monthly; prefixes assigned since then show as not assigned.
Common questions
- What is NPA-NXX?
- The first six digits of a North American number: the three-digit area code (NPA) and the three-digit prefix (NXX). Together they identify the rate center and the carrier the numbers were assigned to.
- What does NPA-NXX stand for?
- NPA stands for numbering plan area, the area code. NXX is the central office code; N is any digit 2 to 9 and X is any digit 0 to 9.
- What does NPA-NXX mean in telecom?
- It is the unit carriers are assigned numbers in. Each NPA-NXX belongs to one rate center, and to one carrier unless the prefix is pooled into 1,000-number blocks.
- Is there a free NPA-NXX lookup for the USA?
- Yes. The tool above reads NANPA's public assignment files for every US prefix, with no sign-up and no upload. It shows the original carrier, not the current one.
- Can I look up an NPA-NXX by zip code or address?
- Not here. Rate centers don't follow zip code boundaries, and NANPA's files don't map prefixes to addresses. The tool works from the number or prefix you enter.
- Is there an NPA-NXX lookup API?
- NANPA publishes the files, not an API. For a live carrier and line-type answer per number, use a carrier lookup API such as the one in the Email + Phone plan.
Sources
The numbering plan only knows what a range was issued for.
In the US and Canada mobiles and landlines share the same prefixes, and anywhere a number can be ported or reassigned the range stops telling the whole story. A live carrier lookup asks the network data instead, which is what the Email + Phone plan adds.
- 5,000 live carrier lookups a month: real line type, including US numbers
- Carrier name for every number looked up
- Upload a CSV up to 100,000 rows; emails in the same file get a mailbox check
One plan, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.