Area Code 78 – Isabela/Quirino/Batanes/Nueva Vizcaya/Cagayan Valley
The phone area code for Isabela/Quirino/Batanes/Nueva Vizcaya/Cagayan Valley is 78 (international format +6378). Browse local exchange codes (NXX) and carrier assignments below.
📍 Geographic Location of Isabela/Quirino/Batanes/Nueva Vizcaya/Cagayan Valley
Geographic Coverage and Administrative Jurisdiction
The +63 78 country-code prefix is a geographic National Destination Code (NDC) assigned to the Cagayan Valley region (Region II) in the northeastern part of Luzon, Philippines. This area code covers the provinces of Isabela, Quirino, Batanes, and Nueva Vizcaya, as well as the city of Tuguegarao in Cagayan province. The region is known for its agricultural production, particularly rice and corn, and is home to the Sierra Madre mountain range and the Batanes islands, which are a popular tourist destination.
Primary Cities and Municipalities
Key population centers served by this area code include Santiago City and Cauayan City in Isabela, Tuguegarao City in Cagayan, and the capital towns of Cabarroguis (Quirino), Basco (Batanes), and Bayombong (Nueva Vizcaya). The area code is used for landline and fixed-line services within these localities.
Dialing Formats and Caller Instructions
For local callers within the Philippines, the national dialing format is 0 78 XXX XXXX (the leading 0 is the national trunk prefix). For international callers, the format is +63 78 XXX XXXX. When calling from within the same area code, local numbers may be dialed without the area code, but this depends on the specific telephone exchange and the operator's configuration. Overlays are not currently in effect for this area code, so the 78 prefix remains unique to the region.
Technical and Regulatory Considerations
As a geographic NDC, the 78 prefix is allocated to fixed-line services, including PSTN and some VoIP-based fixed lines. The National Telecommunications Commission (NTC) of the Philippines regulates the assignment of these codes. Number portability is available for fixed-line services, allowing subscribers to retain their numbers when switching providers within the same geographic area. However, moving outside the region typically requires a change of number.
For businesses or individuals planning to contact parties in the Cagayan Valley, it is essential to use the correct international prefix when dialing from abroad. For example, a call to a landline in Santiago City would be dialed as +63 78 682 XXXX (illustrative). Always verify the current number length, which is typically 8 digits after the area code, but may vary for older exchanges.