Back in the 70's and 80's it was all the rage.
I have always had one in my vehicles. When we bought this rig I bought one of those that has all the controls ans speaker and such on the microphone and the rest is really small and hidden under the dash. I have used it a couple of times but not much out there like it used to be. Mine is still there and it comes on every time the ignition switch is on but I rarely hear much going on.
It does have a nice feature of the weather broadcast. I use that occasionally.