How to Stop iPhone Automatically Switching Cellular Data Lines
To stop an iPhone from automatically switching cellular data lines, open Settings > Cellular or Settings > Mobile Data, select Cellular Data, and turn off Allow Cellular Data Switching. Select the preferred SIM or eSIM as the cellular data line before disabling the option. The selected line remains the primary mobile-data connection.
🤔Note:
Turning off Allow Cellular Data Switching disables automatic changes between active cellular data lines, but the second SIM or eSIM remains available for calls and messages.
Steps
- Open Settings on the iPhone.
- Tap Cellular or Mobile Data.
- Tap Cellular Data and select the preferred phone number or SIM.
- Turn off Allow Cellular Data Switching.
- Confirm the selected line under Cellular Data after leaving the settings screen.
Common Issues and Fixes
- The iPhone keeps changing mobile data SIM during calls: Allow Cellular Data Switching may still be enabled. Return to Settings > Cellular > Cellular Data and disable the setting.
- The switching option does not appear: The iPhone may have only one active cellular line, an unsupported carrier setup, or an older iOS version. Confirm that two SIM or eSIM lines are active and update iOS.
- Mobile data stops during calls: The active call may use the line selected for voice service while the other line handles data. Enable Wi-Fi Calling or select the same line for calls and cellular data.
- The wrong line remains selected: The preferred data line may have changed after a SIM setup or iOS update. Open Cellular Data and manually select the required number.
- Switching continues after the setting is disabled: A carrier profile or network registration problem may be involved. Restart the iPhone, install available carrier updates, and check both SIM lines under Cellular.
Quick Tips
- The setting controls automatic data-line changes, not automatic switching between Wi-Fi and cellular networks.
- Disabling Allow Cellular Data Switching can prevent mobile data during a call on the non-data line.
- Data roaming settings remain separate for each SIM or eSIM. Check Cellular Data Options for the selected line.
- Control Center can change cellular data temporarily, but permanent line selection requires the Settings app.
- A work line and personal line can remain active for calls and messages while only one line provides cellular data.
💡Protip:
If mobile data stops during calls, enable Wi-Fi Calling or select the same SIM or eSIM for both calls and cellular data.
Related Questions
Does turning off Allow Cellular Data Switching disable the second SIM?
No. The second SIM or eSIM remains active for calls and messages. Only automatic cellular data changes are disabled.
How can the preferred iPhone data line be changed?
Open Settings > Cellular > Cellular Data, then select the required phone number or SIM. The selected line becomes the default mobile-data connection.
