Why do I needs SIM card with unlimited data plan?

Global positioning systems (GPS) need subscriber information module (SIM) cards, but they are used to assign subscriber information to a global system for mobile (GSM) communication cellular account. GPS devices require SIM cards to interact with a cellular network in some way, the way devices interact with the network and depending on the type of GPS device.

Thinkrace’s GPS trackers are low-power devices that can be placed in vehicles or carried in a purse or bag. Trackers are used to check locations of children and pets as these devices are capable of transmitting their location to authorized cellular phones or Web sites, depending on the service available.
Some devices transmit audio when the surveillance features are activated, and SIM cards are what allow these to happen: from transmitting location, sending audio data, and receiving commands to turn on audio and other advanced features.