From: j.albert@snet.net   
      
   On 4/21/14 11:33 PM, mroberds@att.net wrote:   
   >   I can   
   > sometimes hear six DTMF tones on the same channel they use for voice,   
   > at about the time that one of the trains should be arriving.  Sometimes   
   > these six tones are shortly followed by one single-frequency tone.  Are   
   > these tones possibly operating the switches at the siding?   
      
   Chances are the tones you're hearing are (for lack of a   
   better word) "hailing" tones. Used either by the train crew   
   to "summon up" the dispatcher's radio and "cue it in" to the   
   right location (near you), or it could be coming from the   
   dispatcher's radio, indicating that he is on the line and   
   ready to communicate.   
      
   If there's a control point involved, the power-operated   
   switches are almost certainly being controlled from the   
   dispatcher's office over a "land line" based CTC system.   
      
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