We are not radio experts. But we need to know Radio's technology. So we'd like to summarize about Radio's technology in our aspect.
Types are based on Frequency.
Family Radio Service (FRS) is an improved walkie-talkie radio system authorized in the United States since 1996. This personal radio service uses channelized frequencies around 462 and 467 MHz in the ultra high frequency (UHF) band.
Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves from 30 MHz to 300 MHz, with corresponding wavelengths of one to ten meters
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 MHz and 3 GHz (3,000 MHz), also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres
TRS(Trunked Radio System)
A trunked radio system is a complex type of computer-controlled two-way radio system that allows sharing of relatively few radio frequency channels among a large group of users
TETRA and Motoloras' iDEN are major systems.
Types are based on Market.
Consumer Two-way Radios (walkie-talkies)
There are venders in the world.