Ok, A little history, Originally GMRS users were assigned a specific frequencies to use. You would license a specific number of mobiles, bases, small bases and repeaters based on the way commercial radio was. GMRS was suppose to be an easy access way to get 2way communications to the masses. It wasnt and still isnt suppose to be a "hobby service" Many 2 way radio shops would put up repeaters and lease time on the repeaters.That has since changed. The FCC rules has since changed to allow all GMRS licensees to use any of the GMRS frequencies. NOTE; FRS and GMRS are different services but share 7 frequencies. GMRS rules apply to GMRS certified radio's and FRS rules apply to FRS radios, For combo radios with both GMRS and FRS in the same radio, The GMRS rules apply when operating on a frequency that is GMRS and FRS rules apply when on a FRS freq. Its gets confusing when your on the shared channel because some radio's are certified as a GMRS on the shared freq and some are certified as FRS on the same freq. ONE OF THE DUMMEST things the FCC has done is allow the combo radios.
Originally Posted by DaveInDenver
There are 23 GMRS frequencies. 7 shared freq, and 8 repeater pairs. the Combo radio's operate on the simplex or repeater output. You may not talk simplex on the repeater inputs. also 2 of the repeater pairs and simplex channels are not legal near the Canadian border. Depending on the freq your on, GMRS is allowed up to 50 watts of power, but only 5 watts on the shared 7 frequencies.
GMRS has no channels assignments, they have freq, What radio channel I choose to make what freq is up to me. If you buy a real UHF radio, not the little toy combo radio, they will have NO frequency programming or set to your needs., You need to have them programmed to your needs.
While they use the word channel is this case they are referring to the radio channel for that freq.
Every GMRS system station operator must cooperate in sharing the assigned channel with station operators in other GMRS systems by monitoring the channel before initiating transmissions, waiting until communications in progress are completed before initiating transmissions, engaging in only permissible communications and limiting transmissions to the minimum practical transmission time.
Please note they 99% off all GMRS users using combo radio violate part of the rules you outlined manly because the radio dont explain how to do it.
Before you transmit you must montior with PL/CTCSS OFF on the channel for other people and wait till they are done, That what the monitor button on radio's are for. If you hear no one then you talk. Again GMRS what not ment to be a chit chat band but a short message type service.
This is any station on the shared 7 frq.
mobile station or small base station operating in the simplex mode*
This is the repeater output or simplex stations
base station, mobile relay station, fixed station or mobile station
This is the repeater input
mobile station, control station or fixed station in a duplex system
The GMRS rules are confusing, 1 because lawyers write them, 2 they are patchwork from old services and 3 they reference other fcc rules that are not in part 95