It is basically a walkie-talkie radio with a SIM card slot, that uses the mobile phone networks to communicate with other network radios.
This means that, unlike "conventional" walkie-talkies, which can only communicate with each other within a couple of miles or so, a network walkie-talkie can communicate over any distance. HUndreds of miles, or down the road, it makes no difference.
This key difference means that network walkie-talkie radios can allow "walkie-talkie style" instant group communications to be available over far greater distances than with "normal" walkie-talkies.
Conventional walkie-talkies do not use an outside network. They are simply radio transmitters that, when the PTT button is pressed, send out a radio signal that can be received by other walkie-talkies on the same channel in the same area.
They are limited because it is not possible for a small, battery-powered handheld radio transceiver to transmit its radio signal very far. Even in "open countryside" conditions, the range of a typical walkie-talkie will only be a few miles at most.
In built-up areas, the range of conventional walkie-talkies may often be less than one mile.
Network radios have none of these range limitations - provided that there is mobile phone signal coverage.
No. they use mobile data to digitise the user's voice and send it via the mobile data networks. They do not make mobile phone calls.