Typical military use half-duplex push-to-talk radio, called combat-net radio. it is not designed like a phone system. This kind of net is very hierarchical, so that commands cannot bypass the chain of command. There are many different radio sets with different capabilities. Most of them don't go through satellites at all. It is very difficult to rely those different kinds of radios, and China don't have that kind of capability. Even for the US military, it will have to wait for the next decades to have the kind of capability for large scale. The keyword is large scale, not just one or two pieces.