Area Code 633 – Sonora
The phone area code for Sonora is 633 (international format +52633). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 633
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Sonora
Geographic Overview and Administrative Scope
Country code +52 (Mexico) prefix 633 is a geographic National Destination Code (NDC) assigned to the state of Sonora, in the northwestern region of the country. The code covers the central and southern portions of Sonora, including the capital city Hermosillo, as well as nearby municipalities such as Ures, Mazatán, and La Colorada. Hermosillo, the state capital and economic hub, is the principal city served by this prefix. The area is known for its industrial and agricultural activities, and the prefix is used for both fixed-line (PSTN) and some VoIP services within this designated geographic region.
Dialing Formats and Instructions
For callers within Mexico, dialing a number in the 633 area requires the national long-distance prefix '01' followed by the area code and the local 7-digit subscriber number. For example, a local call from another state to a Hermosillo landline would be dialed as: 01 633 XXX XXXX. For international callers, the format is: +52 633 XXX XXXX (or 011 52 633 XXX XXXX from the US/Canada). When dialing locally within the same area code, the 7-digit number is dialed directly without the area code or long-distance prefix.
Number Structure and Overlay Considerations
Numbers under prefix 633 consist of a 7-digit subscriber number, making the total national significant number length 10 digits (including the NDC). As of the latest ITU-T E.164 guidelines, Mexico does not use area code overlays in the traditional sense; instead, new geographic numbers are assigned within the existing NDC. However, due to growing demand, some areas in Sonora have seen the introduction of additional NDCs, but 633 remains the primary code for Hermosillo and its surroundings. Callers should always verify the complete 10-digit number when dialing from mobile phones, as Mexican mobile numbers use a different non-geographic scheme.
Caller Guidance and Practical Tips
For local callers within the 633 area, simply dial the 7-digit number. For national callers outside the area, always include the '01' prefix before the area code. For international callers, use the +52 country code and drop the leading '0' of the national prefix. Be aware that some businesses may use VoIP services that display a 633 number, but routing may be IP-based; however, the geographic association remains for regulatory and emergency services purposes. Always confirm the correct number with the recipient, especially when calling from a mobile device, to avoid misdialing.