1. Install the SIM card in your smartphone, check the balance and the Internet.

1. Verify that the SIM card is installed correctly in smart watch.

2. If the Internet connection is established, the balance is positive, please wait until the message “No network” appears on the smart watch screen.

3. Сlick on the message “No network” several times, then will open "APN setting" item.  

4. Check APN parameters with your mobile operator

How to change APN settings - https://elarihelp.freshdesk.com/a/solutions/articles/44001774203/en