Any wireless communication device utilizes a radio-frequency "carrier" which is modulated to transmit analog (voice) or digital (TV. data, etc.) THere are many frequency ranges for different modes to communicate, from "long waves" (10-500 kHz) to short-wave (0.5 to 30 MHz), VHF, UHF, microwaves, mm-waves, now also terrahertz up to IR and optical.
To find out what is used for what, study Radio Communication, Wireless, etc. Find the ARRL Radio Amateur Handbook to learn more.
To "find out" which type of signal is transmitted in a particular frequency band, you need a complex test instrumentation, and a lot of knowledge. Study first!