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The office code protection ended in 1990, but it soon became apparent that this would not free up enough prefixes to meet demand. By the fall of 1990, it was apparent that
Maryland needed another area code. In November 1990, a plan for a second area code, 410, was announced, that would be assigned to
286:
in 1995. While
Maryland would have needed a second area code at some point due to rapid growth in the Washington and Baltimore suburbs, it is very likely that the immediate need for another area code would have been staved off had it been possible to assign more 301 numbers to the Baltimore area
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in which no central office code was duplicated in multiple area codes in the region. Each existing central office code was routed with each area code in the region so that each telephone number in the region could be dialed with any of the regional area codes. The consequence was that the full
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278:), the largest telephone provider in the region, allowed the western part of the state to retain 301 to keep the large number of federal agencies on the Maryland side of the Washington area from having to change telephone numbers. On the other side of the
245:), the state received only one area code. This made Maryland one of the most-populous states to be served by a single area code. By the late 1980s, the rapid growth of the Baltimore and Washington suburbs, as well as the proliferation of
337:, was implemented on March 24, 2012. This had the effect of assigning 24 million numbers to just over four million people. Based on current projections, a fourth area code will not be required in the region until about 2030.
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The number shortage problem was exacerbated by the use of area code 202 as a de facto overlay for the inner ring of the
Washington metro area, even though it was split between three area codes–301, 202, and
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By 2011, the 410/443 area was once again running out of numbers because of the continued proliferation of cell phones. To spare residents another number change to a new area code, a third overlay code,
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the
Baltimore metropolitan area and the Eastern Shore, while western and southern Maryland, including the Washington suburbs, would retain area code 301. Bell Atlantic (now
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Howard County was assigned area code 410, except Mount Airy exchange 829 and Laurel exchanges 210, 317, 490, 497, 598, 604, 725, and 776 remained area code 301.
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was overlaid onto the 410 territory on July 1, 1997. Overlays were a new concept at the time, and had met resistance because of the requirement for
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Although the split was intended to be a long-term solution, within five years 410 was already close to exhaustion due to the proliferation of
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Area code 410 officially entered service on
October 6, 1991; it was initially implemented in a permissive-dialing phase, with
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for local calls across the new 301/410 boundary. The split largely followed metro lines. However, slivers of
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for one numbering plan area, among which 410 was the initial area code for the NPA, when it was
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placed the numbering resources in the danger of exhaustion of central office prefixes.
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capacity of central office prefixes could not be used for each involved area code.
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in 1991. 443 and 667 found assignment primarily in cellular service and for
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and pagers, particularly in and around
Baltimore. To solve this problem,
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List of cities covered and exchanges from Area-Codes.com, 443 Area Code
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List of cities covered and exchanges from Area-Codes.com, 410 Area Code
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310:, a Washington exurb, switched to 410. Effective November 1, 1991,
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was required when calling a different area code in
Maryland.
225:(AT&T) published the first configuration of a nationwide
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exchanges 210, 317, 490, 497, 498, 596, 604, 725, and 778,
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Four counties were split between area code 301 and 410.
617:"Maryland's new 667 area code goes into effect in 2012"
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Anne
Arundel County was assigned area code 410, except
60:. Unsourced material may be challenged and removed.
544:"Nation-Wide Operator Toll Dialing—the Coming Way"
501:Carroll County was assigned area code 410, except
345:The counties served by these area codes include:
894:Telecommunications-related introductions in 2012
889:Telecommunications-related introductions in 1997
884:Telecommunications-related introductions in 1991
511:Frederick County remained area code 301, except
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584:
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181:. The numbering plan area (NPA) includes the
8:
158:'s area codes highlighted in red and blue
120:Learn how and when to remove this message
615:Fazeli Fard, Maggie (October 12, 2011).
265:. This was accomplished via a system of
223:American Telephone and Telegraph Company
534:
479:
477:
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471:
644:"2022-1 NRUF and NPA Exhaust Analysis"
588:"New area code for eastern Maryland".
27:Telephone area codes for east Maryland
353:In the Baltimore metropolitan area:
302:counties, as well as much of western
7:
660:from the original on October 9, 2022
505:exchange 829 remained area code 301.
58:adding citations to reliable sources
203:competitive local exchange carriers
173:(NANP) for the eastern half of the
25:
542:Mabbs, Ralph (Winter 1947–1948).
683:NANPA area code map of Maryland
34:
874:Area codes in the United States
45:needs additional citations for
601:"Now Area Codes Count in Md."
519:exchange 635 was assigned 410.
267:central office code protection
69:"Area codes 410, 443, and 667"
1:
171:North American Numbering Plan
163:Area codes 410, 443, and 667
879:Communications in Baltimore
576:. November 21, 1990. p. E6.
391:A small portion of eastern
189:. The three area codes are
183:Baltimore metropolitan area
910:
605:. November 2, 1992. p. B9.
592:. November 1, 1991. p. 1A.
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572:"New area code coming".
405:Maryland's Eastern Shore
227:telephone numbering plan
548:Bell Telephone Magazine
869:Area codes in Maryland
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231:Operator Toll Dialing
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54:improve this article
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622:The Washington Post
603:The Washington Post
432:Queen Anne's County
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494:exchange 952, and
211:Cavalier Telephone
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857:
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651:nationalnanpa.com
590:The Baltimore Sun
574:The Baltimore Sun
515:exchange 775 and
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422:Dorchester County
327:ten-digit dialing
312:ten-digit dialing
292:ten-digit dialing
259:Northern Virginia
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16:(Redirected from
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239:Washington, D.C.
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437:Somerset County
412:Caroline County
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677:External links
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653:. April 2022.
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442:Talbot County
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304:Howard County
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287:before 1990.
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284:area code 540
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280:Potomac River
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243:area code 202
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235:area code 301
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221:In 1947, the
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199:area code 301
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191:overlay codes
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187:Eastern Shore
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71: –
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66:
65:Find sources:
59:
55:
49:
48:
43:This article
41:
37:
32:
31:
19:
18:Area code 443
830:area codes:
791:area codes:
789:Pennsylvania
780:area codes:
764:
747:
742:
733:
716:
707:
702:area codes:
664:November 30,
662:. Retrieved
650:
638:
626:. Retrieved
620:
610:
602:
597:
589:
573:
568:
556:. Retrieved
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513:Union Bridge
456:
417:Cecil County
402:
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378:Anne Arundel
352:
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296:Anne Arundel
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272:
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247:fax machines
220:
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52:Please help
47:verification
44:
805:610/484/835
793:215/267/445
743:410/443/667
738:301/240/227
725:484/610/835
708:410/443/667
704:301/240/227
517:New Windsor
427:Kent County
319:cell phones
863:Categories
529:References
503:Mount Airy
496:Fort Meade
205:, such as
175:U.S. state
167:area codes
80:newspapers
363:Baltimore
359:Baltimore
828:Virginia
778:Delaware
700:Maryland
655:Archived
628:July 23,
558:July 20,
554:(4): 181
492:Marlboro
388:counties
376:Most of
373:counties
341:Coverage
185:and the
179:Maryland
156:Maryland
852:804/686
848:757/948
844:703/571
840:540/826
817:814/582
809:717/223
801:570/272
769:757/948
721:717/223
403:All of
382:Carroll
371:Harford
367:Calvert
357:All of
300:Carroll
276:Verizon
217:History
207:Comcast
169:in the
94:scholar
488:Laurel
457:
386:Howard
251:pagers
96:
89:
82:
75:
67:
765:South
717:North
658:(PDF)
647:(PDF)
466:Notes
197:from
195:split
101:JSTOR
87:books
748:East
734:West
666:2022
630:2012
560:2023
384:and
369:and
361:and
298:and
249:and
229:for
209:and
73:news
836:434
832:276
821:878
813:724
797:412
782:302
752:302
263:703
261:'s
177:of
56:by
865::
850:,
846:,
842:,
838:,
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819:,
815:,
811:,
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803:,
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767::
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736::
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706:,
649:.
619:.
581:^
552:26
550:.
546:.
474:^
407::
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365:,
668:.
632:.
562:.
241:(
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117:(
112:)
108:(
98:·
91:·
84:·
77:·
50:.
20:)
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