Area Code Overlay and 10-Digit Local Dialing

The following information has been provided by CenturyLink to San Juan County

Overview - Description

  • An Area Code Overlay is the addition of another area code to the same geographic region as an existing area code.
    • An Area Code Overlay does not require existing customers to change their existing area code or their 7-digit telephone number.
  • To ensure a continuing supply of telephone numbers, the Washington Commission has approved an Area Code Overlay, adding the 564 area code to the same geographic region served by 360, 206, 253 and 425 Area Codes.
  • The Area Code Overlay becomes effective January 28, 2017.
    • Permissive dialing begins 01/28/17.
    • Mandatory dialing begins 07/29/17.
    • New Telephone Lines or Service may be assigned using the new 564 Area Code beginning 8/28/17.
  • The following are the affects of overlaying the 564 area code in the 360, 206, 253 and 425 Area Code regions:
    • The 564 area code overlay will be introduced initially in the existing 360 area code region, and then expanded to the 206, 253 and 425 area codes when those areas are nearing exhaust.
    • Neighbors across the street from each other could have different area codes.
    • A customer's second line could have a different area code than the first line.
    • New lines being connected in these areas could have either a 360, 206, 253, 425 area code or a 564 area code once expanded beyond the 360 area code.
    • 10-digit dialing for all local calls in the overlay area is required.
      • To complete local calls in western Washington, the new dialing procedure requires callers to dial the area code + the 7-digit telephone number. This means that all calls in the 206, 253, 360 and 425 area codes that are currently dialed with 7 digits will need to be dialed using 10 digits. The same dialing procedure will apply to telephone numbers assigned from the new 564 area code.  
  • The overlay affects all customers in the State of Washington calling these Area Codes.  

Overview – Recorded Announcements

At the time of mandatory dialing, if a local call is dialed using 7-digit dialing, the following announcement will be provided:

This local call now requires 10 digits. It is not necessary to dial a 1 when calling this number. Please redial using the correct area code

Process - Dialing

  • Permissive dialing begins 01/28/17.
    • The permissive dialing period allowed customers time to become accustomed to using 10-digit dialing for all local calls, and to prepare or reprogram equipment before mandatory dialing begins.
    • From 01/28/17 through 08/27/17, customers located in the overlay area began using 10-digit dialing for all local calls.
    • If the customer forgot and dialed with seven digits, the call still was completed.
  • Mandatory dialing begins 07/29/17.
    • After mandatory dialing takes effect, it becomes necessary to use 10-digit dialing for all local calls.
    • If the customer forgot and dialed with seven digits, the call will not be completed.
    • The customer will hear a recorded message that instructs them to hang up and dial again.
  • All three-digit dialing, such as 911 and 411, does not change, and customers will continue to dial using just the three digits.
  • There are no changes to 500, 700, 800, 877, 888, 900 type numbers.
  • All long distance calls require 1 + ten-digit dialing.
  • Local dialing areas remain the same.
    • The Area Code Overlay does not affect local calling areas.
    • Rates for local telephone service and long distance are not affected by the Area Code Overlay.
  • The following table shows the dialing plan for Washington that becomes effective with mandatory dialing (07/29/17).


Type of Call

Calling To

Dialing Plan


Local Call

Same Area Code

Ten digits

Area Code + XXX-XXXX

Local Call

Different Area Code

Ten digits

Area Code + XXX-XXXX

Long Distance Call

All Area Codes

1 + Ten digits

1 + Area Code + XXX-XXXX

Operator Calls (such as Collect, Third Party)

All Area Codes

0 + Ten digits

0 + Area Code + XXX-XXXX

 Process – Customer Actions


  • Verify their telephone equipment is capable of completing calls to the new 564 area code.
    • New area codes across the country, like the new 564 area code, use a different format than area codes in the past, which could only have a “1” or a “0” as the middle digit.
    • Some telephone equipment used by businesses will not recognize the new area code until that equipment has been reprogrammed or upgraded.
  • Program or upgrade equipment if their business uses specialized communications equipment such as a PBX, electronic telephone sets, auto-dial systems or multi-line key systems.
  • Include the area code with their telephone number if it appears on things such stationery, business cards, signs, and advertisements.
  • Make their customers aware that they may need to make changes to their equipment to recognize the new 564 area code.
  • Customers who subscribe to an alarm service should notify their alarm company of the 10-digit dialing requirement for local calls. 

Who may you contact with questions?

If you have any questions regarding information provided in this notice, please call Centurylink IP Voice Service. Residential customers call 800-788-3500 and Business customers call 800-786-6272 or access the following website for more information: Washington Utilities and Transportation Commission.