Area codes 306, 639, and 474

Area codes 306, 639, and 474 are telephone area codes in the North American Numbering Plan (NANP) for the entire Canadian province of Saskatchewan. Area code 306 is one of the original North American area codes assigned in 1947. Area codes 639 and 474 were added to the numbering plan area in creation of an overlay complex for the entire province in 2013 and 2021, respectively. The incumbent local exchange carrier is SaskTel.

History
When the American Telephone and Telegraph Company (AT&T) created the first nationwide telephone numbering plan in the second half of the 1940s, the United States and Canada were divided into 86 numbering plan areas. Saskatchewan received area code 306 in 1947.

By the mid-2000s, area code 306 came under the threat of central office code exhaustion because of demand for telecommunication services from the proliferation of cell phones and other mobile devices requiring unique telephone numbers, particularly in Regina and Saskatoon.

In long-term nationwide planning in October 2010, the Canadian Radio-television and Telecommunications Commission (CRTC) tentatively reserved a group of new area codes for future relief of existing numbering plan areas that were expected to exhaust in the next 25 years; area code 474 was set aside for relief of area code 306 in Saskatchewan.

In early 2011, a routine analysis by the Canadian Numbering Administrator (CNA) revealed that area code 306 had experienced an unforecasted surge in telephone number allocation and was at risk of exhaustion within three years (a situation referred to as a "jeopardy condition"). In response, the CRTC immediately initiated relief planning measures.

The planning committee considered various options, including a north–south split of the 306 area code. Under this plan, half of the province would keep the 306 area code, while the other half would transition to a new area code. Ultimately, the committee determined that an overlay area code was overwhelmingly better. Given the CRTC's decision the year before, the committee's initial planning document (dated May 18, 2011) recommended the assignment of area code 474 for this purpose, mirroring an assumption that had already been reported in the press.

By the time the committee's planning document was finalized on July 13, 2011, the recommended new area code had changed to 639, an option that was regarded as equally technically viable. The document did not address this divergence from the CRTC's prior allocation nor give a reason for the change, but news reports suggest that it was SaskTel who made the decision to eschew 474, citing a sensitivity to tetraphobia in the community, and that the choice of 639 as a replacement was based on its mathematical similarities with the existing area code.

The proposal to implement 639 as an overlay had the effect of allocating 15.8 million numbers to a province of just over a million people. However, SaskTel and other carriers wanted to spare existing subscribers, particularly in rural areas, the expense and burden of changing their numbers. Overlays have become the preferred method of area code relief in Canada; no area codes have been split in the country since 1999.

On August 26, 2011, the CRTC accepted the relief planning committee's recommendation. Ten-digit dialing was phased in for area code 306 starting on February 25, 2013. On that date, a permissive dialing period began during which seven- and ten-digit calls could complete. Ten-digit dialing became mandatory in Saskatchewan on May 11, 2013, two weeks before the in-service date of May 25. Beginning on September 26, 2013, standard error intercept announcements resumed. Until the implementation of the overlay, Saskatchewan was the last of Canada's original NPAs where seven-digit dialing was still possible.

In July 2018, area code 474 was reserved as a future area code for all of Saskatchewan, as area codes 306 and 639 are expected to exhaust their central office prefixes as early as June 2022. The in-service date of area code 474 was October 2, 2021, with no changes in the established dialing procedure.

Service area and central office prefixes

 * Arborfield: 306–768
 * Balgonie: 306–702 771
 * Battleford: -See North Battleford
 * Beauval: 306–288
 * Borden: 306–997
 * Bredenbury: 306–620 898
 * Buchanan: 306–592
 * Calder: 306–742
 * Canora: 306–563
 * Carrot River: 306–401 768
 * Central Butte: 306–796
 * Churchbridge: 306–896
 * Colonsay: 306–255
 * Craik: 306–734, 639–208
 * Dalmeny: 306–254
 * Dubuc: 306–877
 * Esterhazy: 306–701 745
 * Estevan: 306–308 339 340 415 421 461 471 634 636 637 687, 639–450 534
 * Eston: 306–402
 * Eyebrow: 306–759
 * Foam Lake: 306–272
 * Fort Qu'Appelle: 306–331 332 804 900
 * Francis: 306–245
 * Goodeve: 306–876
 * Grayson & Crooked Lake: 306–794
 * Hague: 306–225
 * Hanley: 306–544
 * Hudson Bay: 306–470 865 600
 * Humboldt: 306–231 289 320 366 367 368 598 682 944, 639–535
 * Invermay: 306–493
 * Kamsack: 306–542 591
 * Kelvington: 306–327
 * Kindersley: 306–379 430 460 463 512 604 806 838 965 967 968, 639–539
 * Kenaston: 306–252
 * Langenburg: 306–496 740 743
 * Lemberg: 306–335
 * East Lloydminster: 306–214 307 603 808 820 821 825 830 875, 639–536 840
 * Lumsden: 306–731, 639–392
 * Luseland: 306–372
 * Marquis: 306–788
 * Meadow Lake: 306–234 236 240 304 819, 639–537
 * Meath Park: 306–929
 * Melfort: 306–275 277 346 752 863 920 921
 * Melville: 306–607 705 707 720 728 730 748 760
 * Milestone: 306–436, 639–440 450
 * Mistatim: 306–889
 * Moose Jaw: 306–214 313 556 624 630 631 681 684 690 691 692 693 694 704 756 905 972 983 990, 639–538
 * Neudorf: 306–748
 * Nipawin: 306–862
 * Norquay: 306–594
 * North Battleford: 306–208 317 386 407 440 441 445 446 470 480 481 490 499 817 906 937
 * Pelly: 306–595
 * Pilot Butte: 306–584 586 781
 * Porcupine Plain: 306–278
 * Preeceville: 306–547
 * Prince Albert: 306–314 557 703 763 764 765 904 922 930 940 941 953 960 961 970 980 981 987, 639–314 533 760
 * Prud'homme: 306–654, 639–653
 * Radisson: 306–827, 639–913
 * Regina: 306–201 205 206 209 216 337 347 351 352 359 450 501 502 503 509 510 517 519 520 522 523 525 526 527 529 530 531 533 535 536 537 539 540 541 543 545 546 550 551 552 559 564 565 566 569 570 580 581 584 585 586 591 596 719 721 737 751 757 761 766 775 777 779 780 781 787 789 790 791 797 798 807 908 910 924 926 936 949 988 992 993 994 995 999, 639-221 316 444 528 560 571 590 600 601 602 603 604 605 606 607 608 609 625 640 641 642 643 644 645 646 647 648 649 739 740 888 915 955 997 999
 * Rhein: 306–273
 * Rocanville: 306–645
 * Rose Valley: 306–322
 * Rouleau: 306–776, 639–394
 * Saltcoats: 306–744
 * Saskatoon: 306–200 202 203 220 221 222 227 229 230 241 242 244 249 250 251 260 261 262 270 280 281 290 291 292 321 341 343 361 370 371 373 374 380 381 382 384 385 477 491 500 514 518 612 649 651 652 653 655 657 659 664 665 667 668 683 700 713 715 716 717 803 844 850 866 875 880 881 899 902 912 914 931 933 934 938 952 955 956 964 966 974 975 977 978 979 985 986 996 998, 639–220 317 470 471 480 630 635 887 916 994 996 998
 * Sheho: 306–849
 * St. Isidore-de-Bellevue: 306–423
 * Stockholm: 306–793
 * Strasbourg: 306–725, 639–914
 * Sturgis: 306–548
 * Swift Current: 306–315 437 712 741 750 770 772 773 774 778 816 907 971 973, 639–541
 * Theodore: 306–647
 * Tisdale: 306–873
 * Unity: 306–228
 * Uranium City: 306–498
 * Wadena: 306–338
 * Watrous: 306–917 946, 639-395
 * Weyburn: 306–405 504 509 809 842 848 861 869 870 891 897 908
 * Wynyard: 306–554
 * Yorkton: 306–316 521 620 621 641 708 782 783 786 818 828 890 909, 639–540
 * Premium services: 306/474/639–976.