Apple built in the ability to use more than one carrier with the iPhone 12 and without the need to swap SIM cards. In fact, this is possible with every iPhone released since 2018. While this can be quite convenient when traveling or switching carriers, allowing a mix of 5G and LTE, it does requires setting up and not every combination of carrier services is compatible. Here's an explanation on how it works and what is needed for anyone that uses an iPhone for work, at home and when traveling.

There are circumstances when the option of using a second carrier is invaluable. For example, when traveling to another country, some cellular plans charge incredibly high rates for calls, texts and data. If a local carrier option is available, an iPhone user may be able to add that service while still being able to switch to their normal carrier in situations when that works better. In other instances, there may be interest in switching to a plan offered by a competing company, but some overlap of services allows an opportunity to test the new service before canceling the old one. T-Mobile recently announced a free test drive so iPhone owners could try their offering before buying. Using a second line for work is also a good reason to make use of this additional SIM support.

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An iPhone can use more than one Subscriber Identity Module (SIM card) but there are some notable limitations. The tray that Apple uses in every iPhone sold in North America only has room for a single SIM card. In order to use more than one carrier, Apple's eSIM technology is required and not every carrier supports this. However, it is possible to use a physical SIM and an eSIM in the same iPhone. Also, multiple eSIMs can be stored and it is relatively easy to switch between carriers regardless of whether the SIM is physical or electronic. Of course, the iPhone must be unlocked to be able to use a second carrier. If it isn't already, the company it is locked to must legally allow unlocking. Each SIM card uses its own phone number and its own data plan, making it possible to split time and charges across multiple carriers, choosing the best for each particular need.

iPhone Dual SIM Setup & Use

SIM tray iPhone 11

A physical SIM card must be inserted in the tray in the recessed slot on the side of the iPhone. A SIM card eject tool or a paperclip can be inserted into the small hole to access the SIM tray. The newer system, eSIM, is handled electronically and installation varies by carrier. Some provide a QR code that is scanned by the camera app, some have a carrier app and can assign the plan to an iPhone remotely, and some require manual setup. Instructions should be provided by the carrier service. If more than one phone number is available, it's important to choose which is the default (or primary) number to use when it isn't otherwise selected. To be able to answer calls from any of the phone numbers associated with the SIMs in the iPhone, Wi-Fi calling or cellular data switching must be enabled. These options can be found in Settings app under the Cellular tab. When two or more plans are active, each can be labeled to make it easy to know which is in use, with 'work,' 'travel,' and 'personal' being good suggestions.

Each person listed in the Contacts app can have a preset call-from number making it effortless, for example, to call business associates with the work line and friends with the personal line. It's also possible to choose which number to call from when using the phone. The option to switch will appear at the top of the dialer. A similar option appears near the top when sending a text. Only one data plan and its SIM is active at a time, but it can be different from the SIM used for the active call and text plan. This allows more flexibility when shopping for a carrier. The status area at the top of the iPhone will show the signal strength for the primary and secondary SIMs, along with status icons that indicate what is currently active for calls, texts, and data. Overall, Apple's dual SIM and eSIM capability allows extra flexibility and potentially could result in savings for iPhone users.

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Source: Apple