Check with your county extension agent. I hunt varmints in Cen Tex using a boom box with detachable speakers and use an outdoor speaker with 25 ft cord. I hunt out of deer blinds using jackrabbit, cottontail, or distressed woodpecker tapes. A small cassette player near your blind should also work. Best time to call is early morning or late afternoon around sunset.
Cloudy days are better.
There are several web sites with varmint hunting info. Leave your email and I will list some or type varmint hunting or varmint calling on your search engine.