With Dual SIM, you can have two SIM cards in one phone, with a different network on each if you wish. Apple finally introduced dual-SIM capabilities on its iPhone XS and XR models, meaning you can now have two different phone numbers associated with a single iPhone.
Have one number for business and another number for personal calls on the same phone
Add a local data plan for when you travel to another country/region
Have separate voice and data plans, cherry picking the best offers from different networks.
Setting up your phone with eSIM
On iPhone models that support it, the eSIM provided by your network is stored digitally.
Go to Settings, then Cellular, then tap Add Cellular Plan.
Position your iPhone so that the QR code provided by your network appears in the frame, or enter the details manually. You may be asked to enter a confirmation code provided by your network.
Tap Add Cellular Plan.
If the new plan is your second phone line, follow the onscreen instructions to set up how you want the plans to work together.
Alternatively, you can activate your plan through your network's app (if supported). Go to the App Store, download your network's app, then use the app to buy a plan.
You can store more than one eSIM on your iPhone, but can only use one eSIM at a time. To switch eSIMs, go to Settings then Cellular, tap the plan you want to use then tap Turn On This Line.
If you have a nano SIM, you can use it as your second phone line. See the Apple Support article Using Dual SIM with an eSIM.
Managing your plans
On iPhones that support Dual SIM, you can choose how your phone uses each line (iOS 12.1 or later).
Go to Settings, then Cellular. Tap Cellular Data and choose a line. You can only choose one line for data - your iPhone will use that line for any activity that requires data when you’re not on Wi-Fi. You may receive roaming charges if Data Roaming is on and you’re outside the region covered by the network. Tap Default Voice Line, then choose a line. Below Cellular Plans, tap a line, then change settings such as Cellular Plan Label, Wi-Fi Calling, Calls on Other Devices, or SIM PIN. The label appears in Phone, Messages, and Contacts.
To register a phone number for iMessage and FaceTime, go to Settings, then Messages and iMessage & FaceTime Line. You can only register one of your phone numbers for iMessage and FaceTime. Your other number can’t send or receive messages using iMessage, or make or receive FaceTime calls. Regardless of the phone number you register, iMessage and FaceTime transfer data on your cellular data line when you’re not on Wi-Fi. Charges may apply.
When using Dual SIM, please note the following:
When you’re on a phone call, any incoming calls on your other line (including calls from emergency services) will go directly to voicemail (if available from your network). You won’t receive missed call notifications. If you set up conditional call forwarding (if available from your network) from one line to another when a line is busy or not in service, the calls don’t go to voicemail - contact your network for setup information
Call waiting will only work for incoming calls on the same line
If you make a phone call from another device by relaying it through your iPhone with Dual SIM, the call will be made using your default voice line
If you start a text or picture message conversation using one line, you can't switch the conversation to your other line. You'll need to delete the conversation and start a new one using the other line. Also, you may receive additional charges if you send text or picture attachments on the line that’s not your cellular data line
Instant HotSpot and Personal Hotspot use the line chosen for cellular data
Choose settings that minimise charges, especially when you travel with your iPhone