Yes, the watches need a SIM card with mobile data (internet megabytes) to function properly.
They are not compatible with duplicate cards, Multisim, or collective plans.
The SIM card can be either contract or prepaid, as long as it includes an active mobile data line.
For SIM cards not from SaveFamily, it’s important to disable the PIN code before inserting the card into the watch, as otherwise, functionality issues may occur.