Regarding GPS Tracking Device with 3G Cell Connectivity - No Monthly Fee

Hi All.

I have seen some GPS Tracking Device which don't need any Monthly Fee for Cell Connectivity. Like Nuzzle.

https://hellonuzzle.com/nuzzle-store/

It have GPS, 3G cell connectivity and embedded SIM Card.
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How it is possible? Any idea what Service they are using which dont charge any Monthly cost?

I saw some M2M IoT SIM Card (Like Telit or other). But I am not sure if that is needed?

Thanks in advance.

Perhaps when you call or send a text message to a phone, information about that phone is sent back to yours.

When you turn on your cell phone it gets registered in the RBS, and to communicate with other phone, this RBS looks for the other RBS where the receiver phone is registered. I think that some information comes back to your phone while calling.

This device could use some free number (services from the provider) to send data.. I don't really know how can they manage to make this without any cost.

Where I live, when you don't pay, you can still receive calls and SMS but cannot answer. Also, when you have to make a call you can add a codification to ask the receiver phone if it will pay the total cost of the call (despite it's receiving a call). Maybe this device ask for other cell phone to pay