This is the Metrolink Mobile Radio Telephone. There are 3 sites with these pairs of channels for that use, but I haven't heard of them on the air in several years. One site is Mt. Emma, just south of Vincent, Oat Mountain, just above Chatsworth and the other was Sunset Ridge, above Pomona. The one on Sunset Ridge is still in place, but the only thing that seems to come out of it, is the Morse Code Base Station Identifier. The "land line" to it is still active, but until the commands to use it in the field are corrected, it is useless. These were put there, primarily for M. of W. use, but occasionally, you would hear a train crew useing them from time to time. There was another site years ago with an output of 26 (160.5 Mhz) but I never knew the input to it. But that one required a digital P.L. tone to access it, where as the other sites mentioned above were carrier squelch, so you could access them with any locomotive radio.