You should power off/on the device when switching SIM cards. A hot swap is not supported by Lumia 1520.
- What Bluetooth profiles are used on my Lumia phone?
- How can I check the IMEI number of my Lumia phone?
- The cable connection between my Lumia phone and computer does not work
- What can I do if the latest Lumia extras are missing on my phone?
- NFC pairing of the Wireless Charging Plate (DT-903) is not working Device Hub, what can I do?