Most smartphones nowadays come with dual SIM support, making it easy to switch between SIMs for calling, texting, or enabling 3G.
To choose the SIM for 3G on Asus Zenfone 3 ZE520KL, follow these steps:
Step 1: Go to 'Settings'.

Access 'Settings'.
Step 2: Choose 'Dual SIM Card Settings'.

Select 'Dual SIM Card Settings'.
Step 3: Choose 'Data Service Network'.

Choose 'Data Service Network'.
Step 4: Choose the SIM you want to connect to the network.

Select the SIM you want to connect to the network.
Wishing you all success.
