the ISP Mobile extenders were set up so that when a trooper was out of his car he could call in on his portable on 155.445 back to the car and then the car would re-transmit the signal back to the post on 42.260Mhz.ISP is now using 800Mhz back to the post and are no longer using the mobile extenders on 155.445.We have heard a couple of Dist 52 and Dist 51 Units talking car to car.