History of mobile systems
As the radio telephony services became more popular,
the insufficient availability of radio frequencies became obvious.
At the 60’s and 70’s, new technologies like dynamic channel
allocation and cell-based networks were developed in order
to decrease the congestion in the radio frequencies.
In the 80’s, several analogue cellular radio networks entered
to service around the world.
Each country has proceeded in its own way in adopting standards
These standards are not mutually incompatible.