Area Code 3657 – Kostopil, Rivne

Geographic Overview

The +380 3657 prefix is a geographic National Destination Code (NDC) assigned to the fixed-line telephone network of Kostopil, a city in the Rivne Oblast (province) of northwestern Ukraine. This numbering area covers the city itself and the surrounding administrative district (Kostopil Raion), which includes numerous smaller towns and rural settlements. The region is part of Ukraine's historic Volyn territory and is served by the national fixed-line operator, Ukrtelecom, as well as alternative licensed operators.

Dialing Formats

When calling a Kostopil fixed-line number from within Ukraine, subscribers must dial the national trunk prefix '0', followed by the area code '3657' and the subscriber's 5-digit local number. The complete national format is: 0 3657 XX XX XX (e.g., 0 3657 1 23 45). From abroad, callers must use Ukraine's country code +380, omit the trunk prefix '0', and dial: +380 3657 XX XX XX (e.g., +380 3657 1 23 45). The total number length after the country code is 9 digits, making the full international number 12 digits in length (including the +380 country code).

Caller Instructions

• Local callers: If you are physically within the Kostopil area, you may be able to dial only the 5-digit subscriber number for local calls, depending on your operator's configuration. However, for clarity and reliability, it is recommended to always use the full national format (0 3657 XX XX XX).
• National callers (outside Kostopil): Dial the trunk prefix '0', then the area code '3657', followed by the subscriber number. Example: 0 3657 1 23 45.
• International callers: Dial your country's international access code (e.g., 011 from the US/Canada, 00 from most European countries), then Ukraine's country code '380', then the area code '3657' without the leading '0', and finally the subscriber number. Example: +380 3657 1 23 45.

Administrative and Regulatory Notes

The Kostopil numbering area falls under the jurisdiction of the National Commission for State Regulation of Energy and Public Utilities (NKREKP), which oversees Ukraine's telecom numbering resources. As with all geographic codes in Ukraine, the prefix is tied to a specific physical location, but number portability may allow subscribers to retain their number if they move within the same geographic area or switch operators, subject to regulatory rules. There are currently no overlay codes planned for this area, so the 3657 prefix remains the sole geographic code for Kostopil.