Troopers usually have access to local systems in addition to their own VHF repeaters. In my neck of the woods, they will frequently pop up on MMCCD P25 and even the local Sheriff conventional repeater on occasion. In the Houston County area, I would not be surprised if they have access to AIRS, as RaleighGuy mentioned. They may be able to utilize the NEXEDGE system as well, but I cannot say for certain.