To choose which SIM to use on this dual SIM mobile phone, you need to access the phone's settings, where you can select which SIM to use for calls, messages and mobile data. The device supports two SIMs at the same time, so you can set up one main SIM for each function or choose to use them alternately depending on your needs.

In general, to insert or change SIM cards, you need to remove the back cover and battery, insert the SIM cards into the slots in the orientation shown (with the chip facing down and the cut side facing the right way), then replace the battery and cover. After switching on, in the network or SIM settings you can choose which SIM to activate for calls, messages or data.