It depends on the operator. Some offer an associated SIM card, in addition to an existing tariff. With some operators, this is free or a fraction of the price of standard tariffs. With a suitable operator, the watch can be operated from as little as nothing per month. The average data consumption of the LAMAX WatchY2 is 50 MB per month (1-minute interval for sending location data and 10 messages per day) and the LAMAX GPS Locator is even less.