Chattanooga, July 31, 2025
News Summary
Residents in the 423 area code will be required to dial 10 digits for local calls starting August 5, 2025, due to the introduction of the new 729 area code. This transition arises from the projected depletion of available 423 numbers by 2025. As part of this change, residents are encouraged to prepare for mandatory 10-digit dialing and ensure their contact information is updated. The new area code will serve the same geographical region, including Chattanooga and other nearby cities.
Chattanooga
Beginning August 5, 2025, residents in the 423 area code will be required to dial 10 digits (area code + 7-digit phone number) for all local calls. Any attempts to make calls using only the 7-digit format will not go through and will direct callers to an announcement advising them to redial.
The transition to mandatory 10-digit dialing is part of the rollout for the new 729 area code, which will start assigning new telephone lines on September 5, 2025. This new area code will serve the same geographical area as the current 423 area code, including cities such as Chattanooga, Bristol, Kingsport, Johnson City, and parts of northeastern Tennessee.
Background and Implementation Timeline
The announcement of the new 729 area code was made by the Tennessee Public Utility Commission in 2023, prompted by projections indicating that the existing 423 area code will run out of numbers by 2025. The depletion of 423 numbers is anticipated by the third quarter of 2026.
Initially, the rollout of the new area code and mandatory 10-digit dialing was planned for February 2025, but this was delayed due to infrastructure damage caused by Hurricane Helene. As part of the transition, a permission dialing period will begin on August 5, 2024, during which calls can be completed using either 7 or 10 digits.
Future Considerations
After the 10-digit dialing requirement takes effect, all available numbers in the 423 area code must be exhausted before new 729 numbers can be assigned. The new 729 code is expected to accommodate an additional 34 years of new phone numbers. It is important to note that this transition does not affect emergency numbers such as 911 or other special use numbers like 311 or 988.
Impact on Residents and Businesses
Residents are urged to save their phone numbers in the new 10-digit format moving forward and ensure that automated services, online profiles, and significant documents reflect this change. Business owners have expressed concerns about the potential for confusion among customers as the area code transition occurs.
Historical Context
The 423 area code was originally split from the 615 area code in 1995 to accommodate regional growth in Tennessee. The introduction of the new area code and mandatory dialing formats aims to support the continuing demand for telephone services in the region.
FAQ Section
Frequently Asked Questions
- When will the new 729 area code be assigned?
- The new 729 area code will start assigning new telephone lines on September 5, 2025.
- What are the dialing procedures before August 2025?
- Residents can still make calls using 7 digits until August 5, 2025, after which 10-digit dialing will be mandatory.
- Will the 423 area code still exist after the transition?
- Yes, the 423 area code will continue to exist alongside the new 729 area code until all available 423 numbers have been assigned.
- How should residents prepare for the change?
- Residents should update their contacts to reflect the 10-digit dialing format and ensure any automated services or documents are revised accordingly.
Key Features Summary
| Feature | Details |
|---|---|
| Mandatory 10-Digit Dialing Start Date | August 5, 2025 |
| New Area Code Assignment Date | September 5, 2025 |
| Regions Affected | Chattanooga, Bristol, Kingsport, Johnson City, northeastern Tennessee |
| Projected Depletion of 423 Numbers | Third quarter of 2026 |
| Duration of 729 Code Viability | 34 years |
| Impact on Emergency Numbers | No change |
Deeper Dive: News & Info About This Topic
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Additional Resources
- WBIR: 10-Digit Dialing Starts Next Week
- Wikipedia: Tennessee
- Chattanooga Pulse: New Area Code Coming Soon
- Google Search: Tennessee area code
- Times Free Press: How to Get Ready for 10-Digit Dialing
- Google Scholar: Area Codes in Tennessee
- Mix 104.1: 10-Digit Dialing Required for 423 Area Code
- Encyclopedia Britannica: Telephone Number
- Knox News: New Area Code Tennessee 729
- Google News: 10-Digit Dialing Tennessee
Author: STAFF HERE CHATTANOOGA WRITER
The CHATTANOOGA STAFF WRITER represents the experienced team at HEREChattanooga.com, your go-to source for actionable local news and information in Chattanooga, Hamilton County, and beyond. Specializing in "news you can use," we cover essential topics like product reviews for personal and business needs, local business directories, politics, real estate trends, neighborhood insights, and state news affecting the area—with deep expertise drawn from years of dedicated reporting and strong community input, including local press releases and business updates. We deliver top reporting on high-value events such as Riverbend Festival, Chattanooga Oktoberfest, and Moon River Festival. Our coverage extends to key organizations like the Chattanooga Area Chamber of Commerce and United Way of Greater Chattanooga, plus leading businesses in manufacturing, insurance, and utilities that power the local economy such as Volkswagen Chattanooga, BlueCross BlueShield of Tennessee, and EPB. As part of the broader HERE network, including HEREBristol.com, HEREKnoxville.com, HEREMemphis.com, and HERENashville.com, we provide comprehensive, credible insights into Tennessee's dynamic landscape.
