All new iPhones from 2018 were released with Dual SIM support, but none of them was able to actually use the eSIM in iOS 12, just the physical Nano SIM. But starting with iOS 12.1, you can now use eSIM to have a business and personal plan on your iPhone X S X S ] Max, or X R at the same time
Requirements for Secondary Line Activation
The setup can be quite confusing as the digital eSIM for the iPhone is a completely new thing. First, you obviously have to have either an iPhone X S
X SMax or X R with dual SIM compatibility. Next, you need to have iOS 1
You must also have an unlocked iPhone X S X S Max, or X R for plans from two different vehicles at the same time otherwise you must use the same carrier – the one with which you already have a plan. In the US, only AT & T, T-Mobile, and Verizon Wireless support the eSIM in your iPhone, but you may need to wait for an update of them before you can use it. Sprint has also hinted that they will support eSIM sometime in the near future.
Another very important thing to mention is that if you use Sprint or Verizon Wireless, a CDMA provider, as your first activated line, your second SIM will support no other CDMA account, according to Apple. This means that you need to use a GSM-based plan as secondary while your iPhone is unlocked. If you bought your iPhone directly from Apple or Verizon, it will be unlocked and in most cases it's the same for Sprint.
While You Can Only Use Two Cellular Plans At the same time, you can use only one at a time on your newer iPhone model when making or receiving calls. If you receive another call from the opposite plan, it will not try to break through, but instead go straight to voicemail. So think about it.
Also, remember that you can have more than one plan for the eSIM, but only one can be in focus, which means that the other plans can not be used until you manually enter them Between your current eSIM plan and another eSIM plan on your device.
You probably already have your primary cellular plan on your iPhone X S  X S Max or X R on your Nano-SIM, so to add a secondary plan like a working account, a local data plan in another country, if you're traveling, or a separate data plan, just because you're looking for a few examples to read a QR code from your carrier, use the app of your carrier or enter the information manually.
Before you leave However, we recommend that you contact your mobile service provider to transfer your current Nano SIM account to the eSIM so that it is easier to insert a Nano SIM card. If you do not care, you can simply activate a second or third line on the eSIM itself.
If you receive a secondary plan from either your current wireless service provider or another wireless service provider (if you have an unlocked iPhone), consider using a QR code Get code either in person on a receipt or by email, which you can scan to easily set up the plan.
Once you have the QR code, open it the app settings, tap on "Cellular", then "Add cellular plan". Next, scan the QR code, and that's it. You may be asked to enter a verification code your provider would have given you. Use it to complete the process as needed.
In some cases, you can buy a secondary plan directly from your mobile service provider's app on your iPhone. In the US these are myAT & T, my Sprint Mobile, T-Mobile or My Verizon. Each app will be different, so you need to figure out how to buy a secondary plan with it. During the process, you can set it up directly on your eSIM.
You can not use the Sprint or Verizon app to purchase a secondary line if you are already on a CDMA network. If you use AT & T or T-Mobile as your first enabled line, you can set up a CDMA-based version as a second plan with the Sprint or Verizon app, or you can use the AT & T to create another GSM-based line set up or T-Mobile App.
Option 3: Enter the Information Manually
If the above two options are not available, you can manually enter the information for your secondary line. Open the Settings app, tap Mobile, then tap Add mobile plan. At the bottom of the Scan QR Code screen, tap "Enter details manually".
You must have the SM-DP + address from your wireless service provider. This is the subscription manager data preparation unit for encrypting the user credentials during over-the-air SIM activation. You will also need an activation and verification code.
After the plan has been activated, you must label it so that you can easily identify which plan you are using on your iPhone, your primary, or the one you use just added. You can choose from Primary, Secondary, Personal, Business, Travel, or Cell data, but you can also enter your own custom label.
Click Done to complete the setup. You can change this later in the mobile settings of the plan under "Cellular Plan Label".
Once you've labeled your new line, you'll now need to choose how your two plans work together on your iPhone (see second screenshot above). In the Standard Line screen, you can select one of the following options:
- Use "[First Plan Name]" as the default line. "[Second Plan Name]" will be available for phone and SMS. (This means that your first plan is your primary plan, which is the default for voice, SMS, data, iMessage, and FaceTime calls.) The second plan is for voice and SMS only.)
- Use "[Second Plan Name]" as your default line. "[First Plan Name]" will be available for phone and SMS. (This means that your second plan is the primary one, which is the default for voice, SMS, data, iMessage, and FaceTime calls. The first plan is for voice and SMS only.)
- Use You "[Second Plan Name]" only for mobile data. "[First Plan Name]" will be your default line. (This means that your second plan will only be used for data, which is a good option when you're on the road.) The first plan is the standard for voice, SMS, data, iMessage, and FaceTime calls .)
Now that your iPhone is set up with two different plans that you can use at the same time, you can use them. In the Contacts app, you can assign your SIM account to contacts, so this account is used by default for each person. When making a call, you can change which line is used by default for iMessages and texts, or you can switch when creating a new message. And thats just the beginning.