Area Code 317 – Chittagong

Overview of Area Code 317 (Chittagong)

Area code 317 is the National Destination Code (NDC) for the city of Chittagong (also spelled Chattogram), the principal seaport and second-largest metropolis of Bangladesh. In the international dialing format, the full country code and area code combination is +880 317. This geographic code is assigned to fixed-line (PSTN) services within the Chittagong metropolitan area and its immediate surroundings, administered under the regulatory purview of the Bangladesh Telecommunication Regulatory Commission (BTRC).

Geographic Coverage and Jurisdiction

The 317 area code serves the Chittagong District, including the Chittagong City Corporation area, the port zone, and adjacent suburban areas. As a geographic prefix, it is tied to a specific administrative jurisdiction, and the numbering plan follows the ITU-T E.164 recommendation for Bangladesh, which mandates a maximum of 15 digits for international numbers. Subscribers under this code are typically connected via the public switched telephone network (PSTN), although some operators may also provide fixed wireless access (FWA) services using this code.

Dialing Formats and Caller Instructions

For local callers within Bangladesh, the national trunk prefix 0 is used before the area code. Thus, to call a Chittagong landline from Dhaka or any other part of the country, you would dial: 0 317 XXX XXX (where X represents the subscriber number). For international callers, the process requires the country code and area code without the leading trunk prefix. The correct international format is: +880 317 XXX XXX. For example, a typical Chittagong landline number might appear as +880 317 123 456.

Numbering Plan and Overlay Considerations

Bangladesh employs a closed numbering plan for fixed lines, meaning the subscriber number length is fixed within the area code. The subscriber number for Chittagong landlines is typically 7 digits, resulting in a total national significant number (NSN) of 10 digits (including the area code). At present, there is no overlay code for Chittagong; the 317 code remains the sole geographic code for the city. However, as demand for fixed-line services grows, the BTRC may introduce additional codes or implement number portability, which could affect routing but not the dialing format.

Practical Tips for Callers

When calling from a mobile phone in Bangladesh, it is essential to use the trunk prefix 0 before the area code, as mobile networks require full national numbering. For international callers, always replace the leading 0 with the +880 country code. Ensure you have the correct 7-digit subscriber number, as omitting a digit will result in a failed call. If you are using VoIP services, be aware that some providers may require the +880 format even for domestic calls, so verify your service provider's dialing instructions.