Just pointing out the obvious here, and not wanting you to spend a bunch of cash on a radio that isn't going to work....
There is more required to accessing a trunked radio system than just the radio. There are system keys, radio ID's, etc. The radio will need to be programmed by someone who has the correct system keys for the system, and the radio will be assigned an individual ID number that must be active in the system.
Unless you have that, the radio will not transmit on the system. If you do have someone that can program it for you and they have the system key and access to the controllers to activate the radio, then you are good to go!