[1] 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").
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.
[4][5] 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.
[6] 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.
However, SaskTel and other carriers wanted to spare existing subscribers, particularly in rural areas, the expense and burden of changing their numbers.