Area Code 633 – Tarutung/Dolok Sanggul

Geographic Coverage and Administrative Jurisdiction

Area code 633 is a geographic National Destination Code (NDC) assigned to the North Tapanuli and Humbang Hasundutan regencies in the province of North Sumatra, Indonesia. The principal cities and administrative centers served by this code are Tarutung (the capital of North Tapanuli Regency) and Dolok Sanggul (the capital of Humbang Hasundutan Regency). The code also covers surrounding towns and villages within these regencies, including Siborong-borong, Sipoholon, and Lintong Nihuta.

Dialing Formats and Number Structure

When calling a fixed-line subscriber within the 633 area code, the national trunk prefix 0 is dialed, followed by the area code and the local subscriber number. The complete national significant number (NSN) for a fixed line in this region is 10 digits long, comprising the area code (633) and a 7-digit local number. For example, a local number such as 1234567 would be dialed as 0633 1234567 from within Indonesia.

For international callers, the Indonesian country code +62 is used, and the leading trunk prefix 0 is omitted. Thus, the same number would be dialed as +62 633 1234567 from abroad. When dialing locally within the same area code, callers may often omit the area code and dial only the 7-digit subscriber number, depending on the specific local dialing plan.

Overlay and Numbering Considerations

As of the latest ITU-T and national numbering plan updates, there is no overlay code for the 633 area. The region maintains a single geographic code, and number exhaustion is not an immediate concern due to the relatively low population density and moderate telecommunication demand. However, in line with national policy, the Indonesian Telecommunication Regulatory Authority (BRTI) may introduce overlays or renumbering in the future to accommodate growth.

Caller Instructions

Local callers within the 633 area should dial the 7-digit subscriber number directly. National callers from other parts of Indonesia must dial 0633 followed by the subscriber number. International callers should dial their international access prefix (e.g., 00 or +), then 62, then 633, and finally the subscriber number, omitting the initial 0.

This geographic code is used for traditional PSTN (Public Switched Telephone Network) services, as well as fixed wireless and VoIP services that are assigned geographic numbers. When calling from a mobile phone, the same dialing rules apply, and the call is routed as a national call, potentially incurring standard long-distance tariffs.