You push that little 'talk' button and everything said can be heard by anyone listening on the same frequency. That's very useful for solders and firemen, but not when talking to your date. But today the radio has become the telephone. Conversations are much more private and technical knowledge is unnecessary. Cellphones, you see, are not 'two-way' in the same sense.
Cellphones do both together, making conversation much more natural.
And where two-way radios control static using unsophisticated 'squelch' circuits that turn the speaker off if no words are being received, cellphones use sophisticated microprocessors and noise filters to control sound quality. The biggest difference, however, is that cellphones don't actually connect with each other. Where walkie-talkies and CBs connect directly, cellphones actually connect to a very sophisticated radio 'base station' located close to the user. And as you move from location to location, you actually change from base station to base station. What makes all this possible is the microprocessor, a small computer circuit programmed to look after all the thousands of variables that make two-way radio such a 'black art'.