Area Code 35 – Ang Thong/Phra Nakhon Si Ayutthaya/Suphan Buri

Geographic Coverage and Administrative Jurisdiction

The country calling code +66 followed by the area code 35 designates a specific geographic numbering area within the Kingdom of Thailand. This prefix is allocated to the central region of the country, encompassing the provinces of Ang Thong, Phra Nakhon Si Ayutthaya (commonly known as Ayutthaya), and Suphan Buri. These provinces are part of Thailand's central administrative region, which is characterized by its historical significance and agricultural richness. Ayutthaya, in particular, is a UNESCO World Heritage Site, attracting numerous tourists. The area code 35 is assigned to the provincial telecommunications networks that serve both fixed-line and, in some cases, fixed-wireless services within these jurisdictions.

Dialing Formats and Caller Instructions

For domestic callers within Thailand, the trunk prefix '0' is used before the area code. Therefore, to call a fixed-line number in this region, you would dial 0 35 XXX XXX (where X represents the subscriber's local number, typically 6 to 7 digits). For example, a local number in Ayutthaya might be 0 35 123 456. When dialing from outside Thailand, the international access code of the originating country must be used, followed by Thailand's country code +66, and then the area code without the leading '0'. Thus, the international format for the same number would be +66 35 123 456. It is crucial to omit the trunk prefix '0' when dialing from abroad; otherwise, the call will not connect correctly.

Overlay Considerations and Numbering Plan

Thailand's numbering plan has not implemented overlay codes in this region; the area code 35 is unique to the provinces mentioned. However, as the demand for telecommunication services grows, the National Broadcasting and Telecommunications Commission (NBTC) may introduce additional area codes or renumbering schemes. Currently, the number length for fixed-line services is 9 digits when including the trunk prefix '0' (i.e., '0' + area code + subscriber number). This structure adheres to the ITU-T E.164 recommendation, which specifies a maximum of 15 digits for international numbers, but Thailand uses a shorter format for national numbers.

Caller Instructions for Local and Foreign Callers

For local callers within the same area code, it is often possible to dial only the subscriber number without the area code, depending on the specific local exchange settings. However, for clarity and to avoid misdialing, it is recommended to always include the area code when dialing from a mobile phone or from a different province. Foreign callers should be aware that Thailand's international dialing prefix is '+66' and that the area code '35' must be dialed without the leading '0'. Additionally, when calling from a mobile phone within Thailand, the same domestic format applies, but the call may be charged as a local call if the mobile user is within the same region, or as a long-distance call if outside, depending on the mobile operator's tariff structure.

It is also important to note that some businesses in this region may use VoIP (Voice over Internet Protocol) services, which can present a different caller ID or routing behavior. However, the geographic area code 35 remains associated with the physical location of the telephone exchange, regardless of the underlying technology.