MNP / switching carrier (Mobile Number Portability)
MNP（携帯電話番号ポータビリティ）／乗り換え MNP / norikae
Moving to a different carrier while keeping the same phone number. In shops and advertisements this is commonly called norikae (乗り換え), meaning switching carrier.
MNP lets you change carrier or brand and keep your phone number. In everyday Japanese, shops and advertisements commonly call this 乗り換え (norikae, switching carrier). You start it with your current carrier — either by getting an MNP reservation number, or through a 'one-stop' MNP where the new carrier pulls the information for you.
MNP is about the phone number and the carrier. It is not the same as a Plan Change (staying with the same carrier and only changing your pricing plan), and it is not a Device Upgrade.
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