depends on the beats....sometimes its like a clear the channel special broadcast coming across....and another if for the Fire Dept. it sets off there alarms.......not sure about trains??I've heard some beeping noises 3 times before dispatcher comes on, i guess sorta like sellective call
They still use the old phone patches out there? What a joke...Here in my area there is no beeping, just a simple call, for example Kearney sub to UP 8534 west, the train answers, they exchange the info required, Kearney sub out...UP 8534 west out.
The pbx system on the other hand is a whole different animal, DTMF tones signal the person being called, and I am sure there is DTMF decoder that sets of an alert of some kind, on the radio being "dialed". To be honest I haven't gotten that into the pbx monitoring that far all the DTMF tones and the ani bursts drive me nuts after about 2 minutes. I am willing to record a short sample and send out an mp3, pm me.
CP Rail's system is very similar to most American RR's. It would have to be since we use each others locos interchangibly.
On the D&H, and CP Lacolle Sub, crews dial the dispatcher with 4 DTMF tones on the RTC/Disp call in freq (160.425 where I'm from on the D&H) . Each radio tower had a different combination so you had to know which tower you wanted to call. The tower would respond with two beeps, and then the tower would "ring" three times on the Standby frequency (161.100 where I'm from).
I know that mostly all railways in NA use the AAR channels from how I was reading I was taking it that the RTC gets the tower in a different way but I think I was getting confused. I work for CPR in Alberta Canada and for the 5 subs that we run on it is the same call-in code. from what I saw at one of the rtcs desk it jest shows on the computer screen for the radio system with tower is calling the desk. then the rtc will click on it and that opens the repeater.