Area codes in Round Rock, Texas
Round Rock, Texas uses 2 area codes — 512 and 737. The main Round Rock area code is 512.
Area codes serving Round Rock
Phone numbers in Round Rock are written as ten digits — for example (512) 555-0190 — and fall in the Central Time zone.
How Round Rock came to have 2 area codes
The original Round Rock area code is 512, in service since 1947. As the area ran low on available numbers, an overlay code was added over the same region for new phone lines: 737 (2013). Existing numbers kept their original code — an overlay never forces anyone to change their number — which is why Round Rock now uses all 2 codes and every local call is dialed with ten digits.
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Frequently asked questions
What is the area code for Round Rock?
The main area code for Round Rock, Texas is 512. Round Rock is now served by 2 area codes in total: 512, 737.
How many area codes does Round Rock have?
Round Rock has 2 area codes: 512, 737.
Why does Round Rock have more than one area code?
As Round Rock used up the numbers available in its original area code (512, in service since 1947), additional "overlay" codes were added over the same area so new phone numbers could keep being assigned.
How do you dial a Round Rock number?
Dial all 10 digits — the area code (512 or 737) followed by the 7-digit local number. From abroad, dial +1, then the area code and number.
Sourced from the official NANPA (North American Numbering Plan Administrator) numbering database, current as of August 2, 2026. Refreshed monthly.