The new 928 area code becomes mandatory Tuesday, Jan. 5.
Beginning that day, people who use the old 520 area code will hear "the dreaded recording" telling them to hang up and redial the number using 928, Heather Murphy, public information officer for the Arizona Corporation Commission, said.
At some point, the recording will no longer include the new area code.
"The earliest the recording can be taken off is the end of March," Murphy said, "but it may remain on longer."
The mandatory date was pushed back from Jan. 1 to allow callers to use the old area code through the holidays.
"New Year's Day is a pretty big calling day, and pushing it back still complies with Federal Communications Commission regulations that require area code changes to be done in a certain way," she said.
Last June, the commission voted to split the area served by 520 into two area codes 520 and 928. Since June 23, the Rim country has been in a "permissive dialing period" when both 520 and 928 calls go through.
The new area code was mandated because the 520 area code was running out of available telephone numbers.
Competition in telecommunications and the proliferation of cellular phones, pagers, fax machines and enhanced Internet services are among the reasons the supply of available numbers is dwindling.
The Arizona Corporation Commission opted to split the 520 region into two distinct geographic territories. Basically the change affects all areas outside the Valley except Pinal, Pima, Cochise and Santa Cruz counties, most all of which will retain the 520 area code. In addition to Payson and the Rim country, communities that will change to the new 928 area code are Bullhead City, Camp Verde, Chinle, Clifton, Cottonwood, Ehrenberg, Flagstaff, Gila Bend, Globe, Grand Canyon, Holbrook, Kingman, Lake Havasu City, Mojave Valley, Oatman, Page, Parker, Pinetop, Prescott, Quartzsite, Safford, Sedona, Seligman, Show Low, Snowflake, Somerton, Wickenburg, Williams, Window Rock, Winslow, Young and Yuma.
Communities that will stay in the 520 area code include Ajo, Benson, Bisbee, Bowie, Casa Grande, Cascabel, Coolidge, Douglas, Elfrida, Eloy, Florence, Green Valley, Hayden, Maricopa Village, Maricopa, Nogales, Patagonia, Pearce, Portal, Sacaton, San Manuel, San Simon, Sasabe, Sells, Sierra Vista, Stutonic, Sunizona, Superior, Tombstone, Tucson, West San Simon, Whitlow and Wilcox.
Detailed maps of the affected areas are available on the Corporation Commission's website (www.cc.state. az.us). Click on "area code" under "hot topics." For a list of prefixes that move to the new area code, click on www.cc.state.az.us/utility/ newarea/new-2.htm.
A small number of prefixes assigned to mobile phones and pagers may not change. Murphy advises customers to check with their mobile communications provider to learn how they are implementing the new area code.