Area Code 355 – Tulungagung/Trenggalek

Geographic Coverage and Administrative Jurisdiction

Area code 355 is a geographic National Destination Code (NDC) within the Indonesian public switched telephone network (PSTN), allocated under the country calling code +62. It serves the southern region of East Java Province, specifically the regencies (kabupaten) of Tulungagung and Trenggalek. These administrative areas are located approximately 150–200 kilometers southwest of Surabaya, the provincial capital. The code covers the urban centers of Tulungagung (including the district of Kedungwaru and the coastal area of Popoh) and Trenggalek (including the districts of Kampak and Watulimo). The numbering area is bordered by the NDCs of Kediri (354) to the north, Blitar (342) to the east, and Pacitan (357) to the west.

Dialing Formats and Number Structure

Subscriber numbers within the 355 area code consist of 5 to 7 digits after the trunk prefix, depending on the specific exchange and historical capacity. The complete international dialing format is:

• International: +62 355 XXX XXXX
• National (from within Indonesia): 0355 XXX XXXX
• Local (within the same area): XXX XXXX (omitting the trunk prefix and area code)

For example, a landline number in Tulungagung might be dialed as +62 355 321 456 from abroad, or as 0355 321 456 from other parts of Indonesia. When calling within the 355 area, subscribers can often use the shorter local format, but this depends on the specific exchange configuration.

Caller Instructions

For callers from outside Indonesia: Replace the international access prefix (00 or +) with the Indonesian country code +62, then dial the area code without the leading zero. For instance, to call a Trenggalek number from the United States, dial 011 62 355 followed by the subscriber number.

For callers from other Indonesian regions: Dial the trunk prefix 0 followed by the area code 355 and the subscriber number. Example: from Jakarta, dial 0355 321 456.

For callers within the 355 area: If your telephone exchange supports local calling, you may dial only the subscriber number. However, if you are using a mobile phone, you must always include the area code (0355) even when calling a landline in the same area, because mobile networks route calls based on the full national number.

Overlay and Numbering Plan Considerations

As of the latest ITU-T and national regulatory updates, there is no overlay code for the 355 area. The numbering area remains a single NDC without an additional area code overlay. However, the Indonesian Telecommunications Regulatory Authority (BRTI) has implemented number portability for fixed lines in certain regions, allowing subscribers to retain their numbers when changing operators. This means that the geographic association of a number may not always reflect the physical location of the line, but the area code remains valid for routing purposes.

Practical Usage and Economic Context

Landline penetration in Tulungagung and Trenggalek is moderate, with many businesses and government offices relying on fixed lines. The area is known for marble mining (Tulungagung is a major marble producer) and tourism (such as the beaches of Prigi and Pasir Putih). When contacting local enterprises, using the correct area code is essential for efficient call routing. For international callers, always verify the current number length, as some exchanges may have migrated to 7-digit subscriber numbers.