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Japan ☎️ Landline / Geographic

Area Code 438 – Kisarazu, Chiba

The phone area code for Kisarazu, Chiba is 438 (international format +81438). Browse local exchange codes (NXX) and carrier assignments below.

Current Local Time
16:45:58
Asia/Tokyo • UTC +09:00
Full Dialing Format
+81438
Population 136,166
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Admin Region Chiba
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Elevation 5m
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GPS Coordinates 35.3833, 139.9325
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📍 Geographic Location of Kisarazu, Chiba

Geographic Coverage and Administrative Jurisdiction

The +81 438 area code is a geographic National Destination Code (NDC) assigned to the Kisarazu area in Chiba Prefecture, Japan. This code covers Kisarazu City and its surrounding municipalities, including Sodegaura, Futtsu, and Kimitsu, all located on the Bōsō Peninsula along the eastern shore of Tokyo Bay. Administratively, these cities fall under Chiba Prefecture, which is part of the Greater Tokyo Area. The region is known for its industrial zones, residential communities, and the Tokyo Bay Aqua-Line bridge-tunnel connection to Kawasaki.

Dialing Formats and Caller Instructions

Within Japan, the area code is dialed with a leading '0' (e.g., 0438). For local calls within the same area code, subscribers can dial the 6-digit subscriber number without the area code. However, for calls from outside the 0438 area but still within Japan, callers must dial the full national number: 0438-XX-XXXX. For international callers, the number must be dialed in the international format: +81 438 XX XXXX (or +81-438-XX-XXXX). The subscriber number is six digits long, making the total national significant number (NSN) 9 digits (excluding the trunk prefix '0').

Overlay and Numbering Plan Considerations

As of the latest ITU-T E.164 allocation, the 0438 area code does not have an overlay. The Japanese numbering plan is closed, meaning the trunk prefix '0' is always dialed domestically, even for mobile calls. The 0438 code is part of the geographic numbering plan administered by the Ministry of Internal Affairs and Communications (MIC) and allocated to NTT East and other carriers. No overlay code has been introduced for this area, so the 10-digit domestic format (0 + area code + subscriber number) remains stable.

Practical Examples for Callers

To illustrate, a local call to a business in Kisarazu with the subscriber number 123456 would be dialed as 123456 from within the same area. From Tokyo (area code 03), the call would be dialed as 0438-123456. From the United States, the international format would be 011-81-438-123456. For callers using VoIP or mobile phones in Japan, the same national dialing rules apply: always include the leading '0' and the area code when calling from outside the area. This ensures proper routing through the PSTN.

❓ Frequently Asked Questions

Which cities are covered by the +81 438 area code?
The +81 438 area code covers Kisarazu City and neighboring areas in Chiba Prefecture, including Sodegaura, Futtsu, and Kimitsu.
How do I call a number in Kisarazu from abroad?
Dial your country's international access code (e.g., 011 from the US), then Japan's country code 81, followed by the area code 438 (without the leading 0) and the 6-digit subscriber number. Example: 011-81-438-123456.
Do I need to dial the area code for local calls within Kisarazu?
No, for calls within the same 0438 area, you can dial just the 6-digit subscriber number. For calls from outside the area but within Japan, dial 0438 followed by the subscriber number.
Is the 0438 area code subject to an overlay or upcoming changes?
As of now, there is no overlay for the 0438 area code. The Japanese numbering plan is stable, and no changes are anticipated in the near future.
What is the number length for a full international call to Kisarazu?
The international format includes country code 81, area code 438 (without the leading 0), and a 6-digit subscriber number, totaling 9 digits after the country code. For example, +81 438 123 456.