Rate Centre Lookup

21,763 rate centres across the United States and Canada. A rate centre is the telephone exchange area a number is homed to — the thing that decides which area codes can serve an address, and whether a call between two points is local.

Rate centre	Region	Area codes	Incumbent	LATA	LIR	Blocks	Switches
Annapolis	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	738	ANNAPOLIS, BALTIMORE, BLTMMDCH08Z +27
Arbutus	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	201	ARBUTUS, BALTIMORE, BLTMMDCH08Z +21
Armiger-Gibson Island	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	145	ARMIGER, BALTIMORE, BLTMMDCH08Z +14
Ashton (Baltimore LATA)	MD	227, 240, 301	VERIZON MARYLAND, INC. (9212)	238	—	81	BALTIMORE, BLTMMDCH25Z, BLTMMDCH42Z +13
Baltimore	MD	301, 410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	3,410	ARBUTUS, BALTIMORE, BALTIMORE CHARLES STREET +58
Bel Air	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	336	BALTIMORE, BEL AIR, BLTMMDCH08Z +23
Brooklyn Park-Linthicum	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	131	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +15
Cardiff	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	58	BALTIMORE, BLTMMDCH25Z, BLTMMDCH40Z +11
Catonsville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	446	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +20
Chase	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	119	BALTIMORE, BLTMMDCH25Z, BLTMMDCH40Z +15
Churchville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	91	BALTIMORE, BLTMMDCH25Z, BLTMMDCH42Z +13
Cockeysville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	265	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +24
Columbia	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	499	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +28
Crofton	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	92	BALTIMORE, BLTMMDCH08Z, BLTMMDCH42Z +12
Darlington	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	56	BALTIMORE, BLTMMDCH25Z, BLTMMDCH42Z +12
Dundalk	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	161	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +18
Edgewood	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	206	ABERDEEN, BALTIMORE, BLTMMDCH25Z +18
Elkridge	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	236	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +20
Elkton	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	253	BALTIMORE, BLTMMDCH25Z, BLTMMDCH3MD +21
Ellicott City	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	220	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +24
Essex	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	264	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +19
Fallston	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	134	BALTIMORE, BEL AIR, BLTMMDCH25Z +16
Fork	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	189	ABERDEEN, BALTIMORE, BEL AIR +22
Glen Burnie	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	576	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +25
Glenwood	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	71	BALTIMORE, BLTMMDCH25Z, BLTMMDCH42Z +11
Hampstead	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	89	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +13
Havre de Grace	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	70	BALTIMORE, BLTMMDCH08Z, BLTMMDCH25Z +14
Jarrettsville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	56	BALTIMORE, BLTMMDCH25Z, BLTMMDCH42Z +10
Jarrettsville 941	MD	410	VERIZON MARYLAND, INC. (9212)	238	—	11	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +3
Laurel (Baltimore LATA)	MD	240, 301	VERIZON MARYLAND, INC. (9212)	238	—	215	BALTIMORE, BLTMMDCH40Z, BLTMMDCH42Z +15
Millersville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	57	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +12
New Windsor	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	69	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +9
North Beach	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	67	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +8
North East	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	77	BALTIMORE, BLTMMDCH3MD, BLTMMDCH40Z +14
Odenton	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	189	BALTIMORE, BLTMMDCH40Z, BLTMMDCH42Z +15
Parkton	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	54	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +9
Parkville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	278	BALTIMORE, BLTMMDCH08Z, BLTMMDCH40Z +22
Perryville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	95	BAINBRIDGE, BALTIMORE, BLTMMDCH3MD +13
Pikesville	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	590	BALTIMORE, BLTMMDCH08Z, BLTMMDCH40Z +22
Port Deposit	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	72	BAINBRIDGE, BALTIMORE, BLTMMDCH25Z +13
Prince Frederick	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	176	BALTIMORE, BLTMMDCH40Z, BLTMMDCH42Z +13
Randallstown	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	133	BALTIMORE, BLTMMDCH08Z, BLTMMDCH40Z +17
Reisterstown	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	154	BALTIMORE, BLTMMDCH08Z, BLTMMDCH40Z +17
Rising Sun	MD	410, 667	ARMSTRONG TEL. CO. OF MARYLAND (0216)	238	—	16	BALTIMORE, BLTMMDCH47Z, BLTMMDCHXFX +4
Severn	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	199	BALTIMORE, BLTMMDCH08Z, BLTMMDCH40Z +21
Severna Park	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	304	ANNAPOLIS, BALTIMORE, BLTMMDCH08Z +20
Sherwood Forest	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	64	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +9
Silver Run	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	43	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +9
Solomons	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	91	BALTIMORE, BLTMMDCH40Z, BLTMMDCH42Z +13
Sparks-Glencoe	MD	410, 443, 667	VERIZON MARYLAND, INC. (9212)	238	—	71	BALTIMORE, BLTMMDCH42Z, BLTMMDCH45Z +12

Searching for a place, not a rate centre?

Many places are localities inside a larger rate centre and hold no numbers of their own, so they are not listed above — Clinton, Maryland is part of Washington Zone 16. The Area Codes tab resolves a place name through to whichever rate centre actually serves it.

What These Terms Mean

The fields shown on the area code, rate centre and LATA pages, in plain language.

Rate centre — The exchange area a number belongs to: The telephone exchange area a block of numbers is homed to, and what decides whether a call between two points is local. It is not a city: many places are localities inside a larger rate centre and have no numbers of their own. Clinton, Maryland is part of the Washington Zone 16 rate centre, so its numbers are 227, 240 and 301.
NPA-NXX — Area code and prefix: The first six digits of a North American number. NPA is the three-digit area code, NXX the three-digit prefix — so 416-200 is NPA 416, NXX 200. Knowing the NPA-NXX identifies the exchange a number was issued from.
Thousands-block — A prefix split into ten pieces: A prefix holds 10,000 numbers, which is more than most carriers need, so prefixes are pooled: split into ten blocks of a thousand and handed to different carriers. The block digit is the fourth digit of the number, and A means the whole prefix went to one carrier. This is why 512 has 783 prefixes but 6,011 rows — 512-555-1xxx and 512-555-2xxx can belong to different companies.
OCN — The carrier holding the block: Operating Company Number — a four-character code identifying the carrier of record for a block. Two carriers can share a brand name and still have different OCNs, which is why the tables show the number alongside the name.
ILEC — The incumbent operator for the area: Incumbent Local Exchange Carrier — the established local operator for a rate centre, usually the former Bell company. It differs from the OCN whenever a block belongs to a competitor: a Toronto block can be held by Bell Cellular while the incumbent for the rate centre is Bell Ontario.
LATA — Where a call stops being local: Local Access and Transport Area — the region a call is routed within before it becomes long-haul. The boundaries date from the 1984 Bell System breakup and still shape how calls are routed and rated. A LATA is three digits, though some rate centres are published with a two-digit sub-code appended, shown here as 460.17. Browse every LATA.
LIR — The Canadian equivalent, roughly: Local Interconnection Region — how Canadian carriers divide territory for exchanging traffic. It only applies in Canada, so this field is blank on every US record by definition rather than by omission.
Switch / CLLI — The equipment serving the block: The telephone switch a block is routed through, named by its CLLI code — an eleven-character identifier where the first characters encode the place, as in TOROON01DS0 for Toronto. A switch typed POI is a point of interconnection, where carriers hand traffic to each other rather than serve subscribers directly.
Overlay and split — The two ways to add an area code: A split divides a region and gives part of it a new code, so existing numbers change. An overlay adds a code on top of the same territory, so nobody has to change a number — but everyone has to dial ten digits, since two numbers in the same place can now differ only by area code. 786 overlaid 305 in 1998; 941 split from 813 in 1995.

One limitation worth knowing. All of this describes the block a number was issued from. Number portability means a number can be carried to another carrier while keeping its digits, so the carrier shown is the carrier of record for the block, not necessarily whoever serves that specific line today. Nothing in this data can tell you which — only a live portability lookup can.