Enter an area code and exchange, like 212-555, to see who holds the block, its line type, and which thousands-blocks inside it are pooled to other carriers.
25 free checks a day from this address.
Run the whole file through the free cleaner — it works in this browser, needs no account, and the file is not uploaded anywhere. That covers formatting, duplicates and numbers that cannot be valid.
For the parts a browser cannot do — whether each block was ever allocated, its line type and its original carrier — we will email a trial key for the desktop app: 50,000 numbers, offline, no card, Windows only. It also raises this page from 25 checks a day to 100. Nothing else is sent to you.
Every US and Canadian number has the form NPA-NXX-XXXX. The NPA is the area code. The NXX is the exchange, also called the central office code. Together the first six digits identify a block of 10,000 numbers, from NPA-NXX-0000 to NPA-NXX-9999, that was assigned to one carrier in one rate centre.
Since number pooling, many exchanges are split further into ten thousands-blocks of 1,000 numbers each. A thousands-block can be assigned to a different carrier from the one holding the exchange, so one exchange can contain a landline company, a mobile network and a VoIP provider. This lookup lists those pooled blocks when they differ from the exchange.
The NPA-NXX guide explains the allocation process in full.
exchange
The six-digit NPA-NXX you entered, and whether it is allocated.
carrier
The carrier the exchange block was assigned to, under its trading name.
line_type
Mobile, landline or VoIP for the exchange, from the numbering-plan record, corrected with carrier evidence where the source labels VoIP wholesale blocks as landline.
pooled blocks
Thousands-blocks inside the exchange assigned to a different carrier or line type. A thousands digit not listed has the same answer as the exchange.
US allocations come from NANPA's public assignment records, combined with Phonelint's numbering-plan data for line type. Canada and the Caribbean are covered from numbering-plan data. The lookup reports allocation: who the block was assigned to. Individual numbers that have been ported away since are not reflected; that needs a live query against the porting database, which carriers and paid APIs make.
To check a specific number rather than an exchange, use the carrier lookup. To see every exchange in an area code, start from the US area code index.
An NPA-NXX used to mean one carrier. Number pooling changed that: an exchange can be split into ten thousands-blocks and handed to different carriers. It is not a rare edge case.
| US exchanges | Count | Share |
|---|---|---|
| With at least one thousands-block that differs from the exchange | 141,583 | 62.4% |
| Answered completely by the six-digit record alone | 85,258 | 37.6% |
| Total six-digit exchanges | 226,841 | — |
| Thousands-block records held | 1,311,108 | — |
Counted from Phonelint's numbering table, 1 November 2026.
For roughly three exchanges in five, the NPA-NXX alone does not settle the carrier or the line type. That is why this page lists the thousands-blocks underneath the exchange instead of returning a single row: the seventh digit of the number decides which one applies. A lookup tool that reports only the six-digit record will confidently give you the wrong carrier for a number in a pooled block, and most exchanges are pooled.
Blocks that do not appear in the list inherit the exchange's own record. Line type and carrier come from the original allocation either way, so a ported number can sit somewhere else today.
The difference between a whole exchange and a pooled one is easiest to see side by side. Both of these are live records, and you can reproduce either above.
212-201 — a whole exchange. One record covers all ten thousand numbers. The six-digit answer is the whole answer:
| NPA-NXX | Line type | Carrier | Thousands-blocks differing |
|---|---|---|---|
| 212-201 | landline | Paetec Communications | 0 |
989-998 — a fully pooled exchange. Every one of the ten thousands-blocks carries its own record. A tool that returned only the six-digit row would be answering a question you did not ask:
| Block | Numbers covered | Line type | Carrier |
|---|---|---|---|
| 989-998-0xxx | 9899980000–0999 | mobile | T-Mobile USA |
| 989-998-1xxx | 9899981000–1999 | mobile | T-Mobile USA |
| … through 9xxx | …9000–9999 | mobile | T-Mobile USA |
Records as held on 1 November 2026. Ten blocks in total; the middle rows are elided here, and the tool above lists all of them.
Reading it: the seventh digit of the number selects the block. For 989-998 every block happens to land on the same carrier, which is common when a single carrier takes the whole exchange through pooling. Where blocks differ, they differ in both carrier and line type, and taking the exchange's own record would give you the wrong one.
Four jobs account for most of the traffic to a tool like this.
Rate centre and jurisdiction. An exchange is tied to a rate centre, which historically decided whether a call was local. This page deliberately does not return a rate centre: the mapping is licensed commercial data, and publishing a guess at it would be worse than publishing nothing. The carrier lookup explains that gap in more detail.
Carrier identification before porting. An NPA-NXX tells you who the block was allocated to, which is the starting point for a port request. It does not tell you who serves a specific number today — that is an LRN query against live porting data, and no allocation table can answer it.
Routing and rating. Carriers and dialers key least-cost routing off the exchange. For that use the thousands-block matters, which is the whole reason this page lists them.
List segmentation. Sorting a list by exchange groups numbers by carrier and line type at once. That is the same operation the free bulk cleaner performs across a whole file, and the desktop app does it over 1.88 million blocks offline at about 47,000 numbers a second, measured on a mid-range Windows laptop.
The first six digits of a North American phone number. NPA is the area code and NXX is the exchange, or central office code. Together they identify a block of 10,000 numbers assigned to one carrier.
Enter the area code and exchange above, for example 212-555. The result shows the carrier the block was assigned to, its line type, and any thousands-blocks inside it that were pooled to other carriers.
A block of 1,000 numbers, NPA-NXX-X000 to NPA-NXX-X999. Number pooling lets the administrator assign these smaller blocks to different carriers, so one exchange can be shared between several providers.
Only the carrier the block was assigned to. If the number was ported to another carrier since, the block record does not change. A live lookup returns the current carrier.
Yes, with no account, up to 25 lookups a day, or 100 a day if you add an email address.
Yes, from numbering-plan data. Pooled thousands-blocks are listed where the data holds them.
Clean 50,000 numbers in your browser free, or label millions by line type offline with the desktop app. Neither uploads your list.