MNP One-Stop in Japan Guide

What is MNP, you ask? It stands for Mobile Number Portability and it’s a process that allows you to transfer your phone number from one carrier to another. In Japan, MNP has undergone a significant transformation with the introduction of what’s known as MNP One-Stop. Let’s take a look below at how much easier it is now to keep your phone number when you switch phone/data SIM companies. 

How the regular MNP works 

For regular MNP, switching carriers involves a multi-step procedure:​

1. Obtain an MNP Reservation Number: Users will be instructed to request this number and its expiration date from their current carrier, often involving time-consuming interactions.​ Depending on the carrier, users may be required to request it through their customer portal or call and ask for it.
   
2. Apply with the new carrier: After receiving the MNP reservation number, users will then need to share the details with their new carrier during the ordering process to initiate the transfer.​
   
3. Complete the transition: After the new carrier completes the order, the number would be ported to the new carrier and it would be active once the new SIM plan is activated. Normally, there’s an automatic cancellation of the previous plan once the new SIM is in use.​

How the MNP One-Stop process works

With MNP One-Stop, you can initiate the transfer directly through the new carrier without separately acquiring an MNP reservation number. This change aims to reduce the hassle associated with switching carriers and make it easier and faster to transfer your phone number.

Here’s how it works:

1. Order your new SIM plan with your new carrier: Begin the process by applying for a new contract with your new carrier. During the ordering process, you will be asked to indicate whether you want to keep your current phone number.​ Once you choose to do so, you will be asked to do MNP One-Stop.
   
2. Authorize process: After you select MNP One-Stop to keep your phone number, you’ll be redirected to your current carrier’s platform to authorize the transfer. This step ensures that the transfer is legitimate and verified.​
   
3. Complete order and transfer: Once the order is completed, the new carrier finalizes the transfer, and your service is switched without the need for further action on your part.​
   

Smiles Connect offers MNP One-Stop so you can transfer your phone number from your previous carrier to us smoothly and quickly. No need to make phone calls and no need to go out of your way to obtain and share MNP details. 

Carriers that have MNP One-Stop in Japan

As of March 2025, several major carriers and MVNOs (Mobile Virtual Network Operators) support the MNP One-Stop system, including:​

• Smiles Connect
• SoftBank
• NTT Docomo​
• Ahamo​
• au​
• UQ Mobile​
• Povo​​
• Y!Mobile​
• LINEMO​
• Rakuten Mobile​
• Japan Communications SIM (b-mobile)
• Mineo​
• IIJmio​
• NURO Mobile​
• BIGLOBE Mobile​
• AEON Mobile

Please make sure to confirm with both your current and new carriers to ensure they support the MNP One-Stop process, as participation may vary.

Benefits of MNP One-Stop

With MNP One-Stop, users can experience:

• Simplified process: Reduces the steps involved in switching carriers, making it more user-friendly.​
  
• Time efficiency: Eliminates the need to obtain an MNP reservation number separately, saving time.
  

Considerations of MNP One-Stop

While the MNP One-Stop system offers numerous advantages, it’s important to:​

• Verify eligibility: Ensure both your current and new carriers offer the MNP One-Stop system.​
  
• Understand the terms: Review your carriers’ contract details or potential fees associated with switching carriers.​
  
• Prepare necessary information: Have personal identification and payment details ready to do a smooth transition. This will depend on the carrier.
  

By understanding and utilizing the MNP One-Stop system, users in Japan can more easily navigate the mobile carrier landscape, taking advantage of competitive offers while keeping their existing phone numbers.

Smiles Connect now offers MNP One-Stop

Smiles Connect is a new MVNO service launched by Smiles Mobile Remittance, Japan’s “Absolute number one” mobile remittance provider. Designed specifically for foreigners living in Japan, Smiles Connect offers affordable SIM plans with multilingual customer support, a simple sign-up process and hassle-free payments—no credit card required.

Though new to the market, Smiles Connect delivers top-tier service by offering strong networks: SoftBank for Data plans and NTT Docomo for Voice plans. These two major Japanese carriers are known for their excellent nationwide coverage and consistent connection quality.

Now, Smiles Connect offers the MNP One-Stop system making it easier for their customers to switch from different carriers. 

To learn more about Smiles Connect, click here.