What is what area code is 423?

Area code 423 covers most of eastern Tennessee, including cities like:

• Johnson City
• Kingsport
• Bristol
• Knoxville (partially - some parts of Knoxville are in area code 865)
• Chattanooga (partially - some parts of Chattanooga are in area code 423)

It's important to note that due to the growth of the region, overlapping area codes are common. This means that you might find both 423 and other area codes (like 865) in use within the same city or even neighborhood. You need to know the specific number to be sure of which area code is relevant.