You should power off/on the device when switching SIM cards. A hot swap is not supported by Lumia 1520.
- My phone does not charge
- What is the Transfer my Data application on my Lumia with Windows Phone 8?
- Which transfer methods does the Transfer my Data application support?
- How can I transfer my contacts, messages, calendar entries or photos to my Lumia?
- I cannot download or update apps from Store on my Lumia. How can I resolve this issue?