As stated, DPS generally utilizes whatever regional system is applicable if in some sort of trunking coverage. In Austin, Bastrop, Lee County, Williamson County, Western Counties, Middle Rio Grande…this means GATRRS. In Permian Basin, this means Permian Regional (until it gets absorbed). In Bell County, it means the Bell County system. Etc.
I don't know how they are handling the more strict (Harris) systems such as Abilene, Lubbock, Midland, San Angelo, etc. I know in some cases where they have very few patrolling troopers, they utilize the SO systems. In others, they utilize their conventional stuff.