Does the iPhone support dual-SIM?
Yes. iPhone XS, XS Max, XR and all later models support dual-SIM operation using one physical nano-SIM and one eSIM, or two eSIMs simultaneously. US models from iPhone 14 onward removed the physical SIM tray entirely and rely exclusively on dual eSIM. Regional exceptions apply: in China mainland, eSIM support is limited; Hong Kong and Macao models feature dual nano-SIM slots instead.
You activate the second line through one of three methods: scanning a QR code provided by your carrier, automatic carrier activation via an entitlement server, or eSIM Quick Transfer from another iPhone. Both lines stay registered with their networks, so either number can receive calls and messages without manual switching — but only one line can carry traffic at a time. That is Dual SIM Dual Standby (DSDS), which is what iPhone implements; it is not Dual SIM Dual Active (DSDA), where both radios operate at once.
eSIM provisioning methods
QR code and SM-DP+ activation
The QR code your carrier provides encodes an SM-DP+ server address and an activation code. When you scan it in Settings → Cellular → Add eSIM, iOS contacts the SM-DP+ server, authenticates using the activation code, and downloads the eSIM profile to the device's embedded Universal Integrated Circuit Card (eUICC). This is the LPA (Local Profile Assistant) flow defined in GSMA SGP.22.
The profile contains IMSI, Ki, carrier APN settings, and network authentication credentials. Once installed, the profile appears as a selectable line in Settings → Cellular. You need a Wi-Fi or hotspot connection for activation in most regions; some eSIM-only models activate without Wi-Fi in specific markets.
If the QR code has already been claimed by another device, the SM-DP+ server returns an error and iOS displays "This code is no longer valid." The activation code is single-use by design; you must request a new QR code from your carrier.
Carrier activation
Carriers that support eSIM Carrier Activation provision profiles directly via an entitlement server without requiring a QR code. When you insert a physical SIM or connect to the carrier's network, iOS queries the carrier's entitlement API. If an eSIM profile is available for your account, iOS prompts you to install it.
This flow is common for users upgrading within the same carrier or activating a new line during iPhone setup. The carrier's backend associates your IMEI with an eSIM profile and pushes it to the device when you authenticate.
eSIM Quick Transfer
eSIM Quick Transfer requires both devices to run iOS 18 or later, the same Apple Account signed in, and Bluetooth enabled. During setup of a new iPhone, iOS detects nearby devices and offers to transfer the eSIM profile directly over a local encrypted channel.
The transfer flow:
- New iPhone broadcasts a Bluetooth LE advertisement.
- Old iPhone receives the pairing request and displays a confirmation prompt.
- User taps Transfer on the old device.
- iOS establishes a peer-to-peer Wi-Fi connection (not infrastructure Wi-Fi).
- The eSIM profile is re-provisioned to the new device via the carrier's entitlement server; the old device's profile is deactivated.
This is not a literal profile copy—the carrier's SM-DP+ server issues a new profile to the new device and revokes the old one. If the transfer fails mid-flight, the profile remains active on the original device and you can retry.
You can also convert a physical SIM to an eSIM using Quick Transfer if your carrier supports it. The flow is identical; iOS contacts the carrier's API to provision an eSIM profile and deactivates the physical SIM.
Dual standby behaviour
iOS implements Dual SIM Dual Standby (DSDS), not Dual SIM Dual Active. Both lines register with their respective networks and either can receive calls and SMS while idle, but the device has a single active radio chain: the moment one line is in a call, the other cannot carry traffic. When a call arrives on Line 1 while you are on a call on Line 2, iOS displays a call-waiting notification. You can hold the active call and switch, or decline the incoming call.
Data line selection
Only one line can use cellular data at a time. You designate a default data line in Settings → Cellular → Cellular Data. If the default line loses coverage, iOS can switch data to the secondary line automatically if you enable "Allow Cellular Data Switching." This setting appears only when both lines are active.
When Allow Cellular Data Switching is on and the primary data line has no service, iOS uses the secondary line for data and displays "Using [Line Name] for Cellular Data" in Control Centre. Voice calls on the primary line still route over that line's network when coverage returns.
Call routing
Outgoing calls use the line you select in the Phone app's keypad. Before dialling, tap the current line label at the top of the screen to switch. iOS remembers which line you last used to contact each number and defaults to that line for subsequent calls to the same contact.
iMessage and FaceTime can be enabled on both lines simultaneously. Messages sent to your phone number route to the corresponding line; messages sent to your Apple Account email address appear on both. You can choose which line to use for new conversations in Settings → Messages → Send & Receive and Settings → FaceTime.
The eight-profile limit
The eUICC can store eight or more eSIM profiles, but only two can be active simultaneously. This is a hardware constraint of the eUICC's non-volatile memory.
When you attempt to install a ninth profile, iOS prompts you to delete an existing one. Deleting a profile removes it from the device entirely; you must re-provision it from the carrier (via QR code or entitlement server) to use it again. Some carriers allow you to download the same profile multiple times; others issue a new activation code for each installation.
To delete an eSIM profile:
- Open Settings → Cellular.
- Tap the line you want to remove.
- Tap Delete eSIM.
- Confirm the deletion.
The profile is erased from the eUICC immediately. If the line is active, it deregisters from the network within seconds.
Troubleshooting activation failures
SM-DP+ server unreachable
If iOS displays "Unable to Complete Cellular Plan Change" after scanning a QR code, the SM-DP+ server is unreachable or returned an error. Common causes:
- No internet connection: Activation requires Wi-Fi or an active cellular data connection on the primary line. Connect to Wi-Fi and retry.
- Incorrect QR code: The QR code may be damaged or incorrectly printed. Request a new code from your carrier.
- Server-side error: The carrier's SM-DP+ server may be temporarily unavailable. Wait and retry.
Check the activation code format. A valid LPA QR code begins with LPA:1$ followed by the SM-DP+ address and activation code, for example:
LPA:1$sm-dp.example.com$ACTIVATION-CODE-STRING
If the QR code does not match this format, it is not a valid eSIM activation code.
Profile already claimed
If the activation code has been used on another device, the SM-DP+ server refuses the request and iOS displays "This code is no longer valid." Activation codes are single-use. Contact your carrier to request a new QR code or use their self-service portal to generate one.
Carrier compatibility
Your carrier must support eSIM for the activation to succeed. Apple maintains a list of compatible carriers at apple.com/uk/esim, but the list is not exhaustive. If your carrier is not listed, contact them directly to confirm eSIM availability for your plan.
Some carriers restrict eSIM to specific plan types (e.g., postpaid only) or require account verification before issuing an activation code. Prepaid eSIM availability varies by carrier and region.
APN configuration missing
After successful activation, if cellular data does not work, the APN settings may be missing or incorrect. iOS usually downloads APN settings automatically from the carrier's provisioning server, but manual configuration is sometimes required.
To check APN settings:
- Open Settings → Cellular.
- Tap the eSIM line.
- Tap Cellular Data Network.
If the APN fields are blank, contact your carrier for the correct APN, username, and password. Enter them manually and restart the device.
Device lock status
Carrier-locked iPhones may refuse to activate eSIM profiles from other carriers. Check lock status in Settings → General → About → Carrier Lock. If the device is locked, contact the original carrier to request an unlock. Once unlocked, restart the iPhone and retry activation.
Managing two lines in practice
Choosing a provisioning method
Use eSIM Quick Transfer when moving to a new iPhone and your carrier supports it. This is the fastest method and requires no interaction with the carrier's website or support team.
Use QR code activation when adding a new line from a different carrier, activating a travel eSIM, or when Quick Transfer is unavailable. Request the QR code from your carrier's self-service portal or customer support.
Use carrier activation when your carrier provisions eSIM automatically during account setup or device purchase. This method is common for new lines purchased directly from the carrier.
Labelling lines
iOS prompts you to label each line during activation (e.g., "Personal," "Work," "Travel"). Labels appear throughout the system—in the Phone app, Messages, and Control Centre—making it clear which line you are using. You can change labels at any time in Settings → Cellular → [Line Name] → Cellular Plan Label.
Setting a default line
Designate a default line for cellular data, voice calls, and iMessage in Settings → Cellular. The default data line is used unless you manually switch or enable Allow Cellular Data Switching. The default voice line is used for outgoing calls to contacts not already associated with a specific line.
For contacts you call regularly on a specific line, iOS remembers your choice and uses that line automatically. You can override this per-contact in the Contacts app by editing the contact and setting a preferred line under "Cellular."
International travel
When travelling, you can add a local eSIM without removing your primary line. The local eSIM becomes the default data line, while your primary line remains active for incoming calls and SMS. This avoids roaming charges on your primary line while maintaining reachability.
Disable data roaming on your primary line in Settings → Cellular → [Primary Line] → Data Roaming to prevent accidental data usage. Enable it only on the local eSIM line.
What to do next
Set up dual-SIM by choosing the provisioning method your carrier supports: Quick Transfer for same-carrier upgrades, QR code for new carriers or travel eSIMs, or carrier activation for automatic provisioning. Label both lines clearly in Settings → Cellular so you can distinguish them in the Phone app and Messages. Set a default data line and enable Allow Cellular Data Switching if you need automatic failover when the primary line loses coverage. For international travel, add a local eSIM as the data line and disable roaming on your primary line to avoid charges while remaining reachable on your home number.
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