STARTING May 24, 2021

Calling a 405 number? You’ll need ten digits from now on.

Dial (405) + the seven-digit number.

Plus, an additional 572 area code will start serving the Oklahoma City region starting April 24, 2021.

Who will be affected?

The 405 area code serves all or portions of 19 counties in the central part of the state, which includes Oklahoma City—the state capital and state’s most populous city. The new 572 area code will serve the same geographic area currently served by the existing 405 area code.

Why is the change necessary?

To ensure a continuing supply of telephone numbers, the new 572 area code is being added to the region originally served by just the 405 area code. This is known as an “area code overlay.” An overlay does not require customers to change their existing area code.

Since two area codes will now serve the same geographic region, an area code must be used when dialing any telephone number—including calls within the same area code.

What is the new dialing procedure?

To complete local calls, the new dialing procedure requires callers to dial area code + telephone number. This means that all calls in the 405 area code that are currently dialed with seven digits will need to be dialed using area code + telephone number. The same dialing procedure will apply to telephone numbers assigned to the new 572 area code.

When will this change become mandatory?

Starting May 24, 2021, you must use the new dialing procedure for all local calls. After this date, if you do not use the new dialing procedures, your calls will not complete and a recording will instruct you to hang up and dial again.

Want to get in the habit? Callers can begin using the new dialing procedures as early as October 24, 2020. If you forget and dial just seven digits, your call will still be completed.


Beginning April 24, 2021, new telephone lines or services may be assigned numbers with the new 572 area code.

What will I need to do?

Along with changing your dialing procedures, all services, automatic dialing equipment, or other types of equipment that are programmed with a 7-digit number will need to be reprogrammed to use the new dialing procedures as well. Some examples are life safety systems, PBXs, fax machines, Internet dial-up numbers, alarm and security systems, gates, speed dialers, call forwarding settings, voicemail services, etc. You may also want to check your business stationery or advertising materials to ensure the area code is included.

What will stay the same?

  • Your telephone number, including your current area code, will not change.
  • The price of a call, coverage area, or other rates and services will not change due to the overlay.
  • What is a local call now will remain a local call regardless of the number of digits dialed.
  • You will still dial just three digits to reach 911.
  • If 211, 311, 411, 511, 611, 711, or 811 are currently available in your community, you will still dial just those three digits.

Who can I contact with questions?

If you have any questions regarding information provided in this notice, please call T-Mobile Customer Care at 1-800-T-MOBILE.