Even if you want to have two iPhones, many people hesitate because they feel that they will need another number or that they will be charged double charges. iOS27 is expected to introduce a system where you can set up two iPhones with one phone number and switch between them. For people who want to separate work and personal use, or who want to use a foldable iPhone and a regular model at the same time, the hurdle of owning two iPhones may be much lower. In this article, we will summarize what it can do and whether Japanese users can actually use it.
With iOS27, it is now possible to have “one number and two devices”
The “two iPhones with the same number” rumored in iOS27 is a mechanism that allows you to register one phone number on two iPhones and switch between devices. The main feature is that you can use only the main unit without increasing the number.
According to reports from overseas media, Apple released a list of minor improvements to iOS27, iPadOS27, and macOS 27 Golden Gate at WWDC2026 in June. The list included an item that said, “You can switch between two iPhones using the same phone number.”
The idea is to register two iPhones with one number and switch to the one you want to use. The key point is not to be in constant standby mode where two devices ring at the same time, but to “switch the device you are using.” However, it is currently in beta stage and it is not known to what extent it will be implemented. iOS27 is expected to be officially released this fall, and the focus is first on whether it will be provided in the official version.
Expected usage: carrying two iPhones and folding iPhone
The most obvious case is one person using two iPhones. You can usually carry around the Pro model with its high camera performance, and only take out a thin, lightweight model (such as the iPhone Air) as a secondary device when you want to move around more easily. You can keep the same number and change the main body depending on your mood or purpose.
Don’t miss the combination with the foldable iPhone. According to reports from overseas media, this will likely be a convenient change for people who want to use both the regular iPhone 18 Pro and the foldable model that is expected to be released after this fall. Even if you change your handset, the number displayed to the other party will not change.
Until now, it has not been easy to use the same number on two iPhones. What is new about this product is that it allows you to use different units and unify the number at the same time.
Carrier support is the key – Can it be used in Japan?
What cannot be overlooked is that this mechanism seems to be based on the carrier’s response. Foreign media reports also mention the possibility that carrier support is required to share a number between two iPhones, and that it is unclear whether it will work in the beta version.
For Japanese users, this is probably the biggest concern. As a mechanism for handling multiple numbers, there are already dual SIM, which allows you to put two numbers in one device, and a function that allows iPhone and Apple Watch to share the same number. However, please note that while dual SIM is “2 numbers on 1 device”, the new function is “switching 1 number between 2 devices” in the opposite direction.
As with past number-related functions, it seems that usage requires support from your carrier. Apple’s official information also states that dual SIM requires an eSIM-compatible carrier and, in some cases, the device must be SIM unlocked. Whether you can use the same number on two iPhones will depend on whether companies such as Docomo, au, Softbank, and Rakuten Mobile support the new system.
There is currently no material that can be definitively used in Japan. It is realistic to wait for the release of the official version and the announcement of support from each carrier.
summary
iOS27 is expected to introduce a feature that allows users to switch between two iPhones using one phone number. For people who have two phones or are thinking about using them with a foldable iPhone, being able to use a single number should be a big attraction.
However, it is assumed that carriers will respond, and it is unclear whether it will be implemented in beta. As for when it will be available in Japan, it will be based on the official release of iOS27, which is expected this fall, and the announcement of support from the contracted carriers. If you are concerned, it is safe to follow these two points.
Source: iPhone Mania
