- Ensure the SIM card is properly seated in the tray. Learn to fix any issues you might encounter when using Dual SIM with an iPhone XS, iPhone XS Max, iPhone XR, or later model that features a nano-SIM card and an eSIM or two eSIMs. If you're wondering how to use dual SIM on iPhone, you've come to the right place: with two active lines you can separate work and personal life, travel with a local plan or even combine one voice line and one data line on the same device. While both numbers work for calls, FaceTime, and messages. Please follow steps below on How to use or manage dual-SIM cards on Samsung phone. Update your mobile device's software. 2) Tap on Download and install. Go to **Settings > Connections > SIM Manager** and make sure both SIMs are toggled on.