I travel often between Europe and the US and so have both a UK and US phone numbers/data plans. I use iMessage and FaceTime constantly for business and need to be contactable wherever I am. Currently, I have a main iPhone using the local sim chip and and old iPhone using the foreign sim. I keep the main iPhone with me and the old iPhone at home logged in to WiFI. When I switch countries, I switch sim chips between the phones. This usually works but if the old iPhone runs out of battery (because I forget to charge it since I don’t use it) that number gets unregistered with my AppleID and people can’t contact me.

Im excited to get a new iPhone with DualSim and I understand why only one sim can be used for data, and that you can choose which number iMessage and FaceTime are activated on. However, will both numbers stay registered with iMessages and FaceTime so that messages to both are received across all my AppleID products, or will i need to switch back and forth (the iMessage/FaceTime sim and/or the data sim) to keep them both active?

I have set up dual sim on my 12 mini with an AT&T physical sim as primary, and a Google Fi ESIM as secondary. The Google line will be used once I head overseas, as AT&T is not good internationally. I am wanting people to be able to reach me via iMessage and Voice at my old (AT&T) number while using the Google Fi number for work there. Essentially nothing–both dual SIM and eSIM allow you to have two distinct plans on your iPhone 11, XR, SE (second generation) and XS/XS Max. Both give you two phone numbers to make and receive calls and text messages. However, your iPhone can only use one data network at a time–that’s true for eSIM and dual-SIM phones. Seeing this message is a new feature on these iPhone models that have dual SIM capabilities, including physical and eSIM. It is absolutely normal due to that dual SIM/eSIM functionality available on the iPhone 11 models, XR, XS/XS Max.

You can use iMessage or SMS/MMS to send messages with either phone number. You can switch phone numbers before you send an iMessage or SMS/MMS message. Here’s how: Open Messages. Tap the New button, in the top right-hand corner of the screen. Enter your contact's name. Tap the current phone number. Tap the number that you want to use.

Similarly, after how much time off being logged off does a number get unregistered from your AppleID?

thanks!

Posted on Nov 4, 2018 5:30 PM

What is Dual SIM?

Here are a few of the many ways you can use Dual SIM:

Use one number for business and another number for personal calls.
Add a local data plan when you travel outside of the country or region.
Have separate voice and data plans.

With iOS 13 and later, both of your phone numbers can make and receive voice and FaceTime calls and send and receive messages using iMessage, SMS, and MMS.² Your iPhone can use one cellular data network at a time.

1. eSIM on iPhone is not offered in China mainland. In Hong Kong and Macao, iPhone 12 mini, iPhone SE (2nd generation), and iPhone XS feature eSIM. Learn about using Dual SIM with two nano-SIM cards in China mainland, Hong Kong, and Macao.
2. This uses Dual SIM Dual Standby (DSDS) technology, which means that both SIMs can make and receive calls.

About 5G and Dual SIM

If you have iPhone 12, iPhone 12 mini, iPhone 12 Pro, or iPhone 12 Pro Max, and both phone lines are active, 5G isn't available. To use 5G on these iPhone models, disable Dual SIM mode by turning off either one of your phone lines:

Open the Settings app, then tap Cellular.
Select the line that you want to turn off.
Turn off the switch next to Turn On This Line.

Turn the line back on to return to Dual SIM mode.

What you need

An iPhone XS, iPhone XS Max, iPhone XR, or later with iOS 12.1 or later
A wireless carrier that supports eSIM

To use two different carriers, your iPhone must be unlocked. Otherwise, both plans must be from the same carrier. If a CDMA carrier provides your first SIM, your second SIM won't support CDMA. Contact your carrier for more information.
If you have an enterprise or corporate cellular service plan, check with your company administrator to see if they support this feature.

Set up your cellular plan with eSIM

On iPhone XS, iPhone XS Max, iPhone XR, and later, you can use a physical nano-SIM for a cellular plan and an eSIM for one or more other cellular plans. If you don't have a nano-SIM and your carrier supports it, an eSIM can serve as your only cellular plan. The eSIM provided by your carrier is stored digitally in your iPhone.

To activate your second cellular plan, you can scan the QR code your carrier gave you, use your carrier's iPhone app, install an assigned plan, or you can enter the information manually:

Scan a QR code

Open the Camera app and scan your QR code.
When the Cellular Plan Detected notification appears, tap it.
Tap Continue, at the bottom of the screen.
Tap Add Cellular Plan.

If you're asked to enter a confirmation code to activate the eSIM, enter the number that your carrier provided.

Use a carrier app

Go to the App Store and download your carrier's app.
Use the app to purchase a cellular plan.

Install an assigned cellular plan

With iOS 13 and later, some carriers can assign a cellular plan for you to install. Contact your carrier for more information.

If a plan was assigned to you, follow these steps:

When a notification appears that says Carrier Cellular Plan Ready to Be Installed, tap it.
In the Settings app, tap Carrier Cellular Plan Ready to Be Installed.
Tap Continue, at the bottom of the screen.

Enter the information manually

If necessary, you can manually enter your plan information. To enter your plan information manually, follow these steps:

Go to Settings.
Tap either Cellular or Mobile Data.
Tap Add Cellular Plan.
Tap Enter Details Manually, at the bottom of your iPhone screen.

You can store more than one eSIM in your iPhone, but you can use only one at a time. To switch eSIMs, tap Settings, tap either Cellular or Mobile Data, and then tap the plan you want to use. Then tap Turn On This Line.

The next sections give you more information about the remaining setup screens on your iPhone.

Label your plans

Dual Sim Imessage

After your second plan is activated, label your plans. For example, you can label one plan Business and the other plan Personal.

You'll use these labels when you choose which phone number to use for making or receiving calls and messages, to designate a number for cellular data, and to assign a number to your contacts so you know which number you will use.

If you change your mind later, you can change your labels by going to Settings, tapping either Cellular or Mobile Data, and then tapping the number whose label you want to change. Then tap Cellular Plan Label and select a new label or enter a custom label.

Set your default number

Choose a number to use when you call or send a message to someone who isn't in your Contacts app. With iOS 13 and later, choose which cellular plans you want to use for iMessage and FaceTime. With iOS 13 and later, you can choose either or both numbers.

On this screen, choose a number to be your default, or you can choose which number is to be used only for cellular data. Your other number will be your default. If you want your iPhone to use cellular data from both plans, depending on coverage and availability, turn on Allow Cellular Data Switching.

Use two phone numbers for calls, messages, and data

Now that your iPhone is set up with two phone numbers, here's how to use them.

Let your iPhone remember which number to use

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