What is the PoC Handset Radio?

PoC is an abbreviation of Push-to-Talk Over Cellular.
It means that you can communicate with your partner in one system by 4G/LTE network.
It is a technique of using the mobile phone network , to make calls that conduct like conventional walkie talkie,  with instant access and one to many calls,
one to one call, many to many call, use of the advantage on the world-wide coverage of the cellular phone networks, GSM, 3G, 4G etc.