Dispatchers nowadays, usually have hundreds of miles of territory. I know for example, at one time, UP Dispatcher 28 handled from Joliet, IL all the way down to just North of Baldknob, AR. When this was the case, he had about 32 radio sites. It is impossible to monitor all those sites at the same time, especially with all the talk in the field. Also, with the Dispatchers all being in cubicles right next to each other, the nose level would be so awful that you wouldn't be able to hear yourself think, so these are some reasons the tone call in for contacting a dispatcher, and again, in some areas, Yardmaster are used. The Dispatchers wear communication headsets to communicate. Also, once you send in a tone call, the radio site/tower square shows the word "Call" until it is answered, or acknowledged. There is no neat to repeat the sending of the DTMF tones multiple times, as it doesn't get the call answered faster. However, you can't convince some people in the field of that.
Hey Mister Q, I like your sense of humor, but please keep it clean here on the forum site. Thank You! Also, if you must know, this SP Dispather I refer to hated Santa Fe for some unknown reason, so that is why he told me never to call him a "DS" ever again.