The telephone network at that time used multi-frequency (or MF) signalling almost exclusively when someone made a long distance call. These are similar to Touch-Tones, but use different frequencies and are used in a different manner. [...] Also in the analog telephone switching network, there had to be a way to tell the originating switch (or the switch that handled the billing) to start and stop the billing of a toll call. This was through the use of single frequency (or SF) tones. In North America, this was accomplished with 2600 Hertz, while in England this was accomplished with 2400 Hertz. (Some of you are already getting ahead of me...)
- 3:03.4 2600 Hz answer supervision -- duration .019 seconds pause .125 seconds
- 3:03.5 2600 Hz answer supervision -- duration .018 seconds
(Two bursts of 2600 Hz answer supervision, this means the call was going through two tandems. Again you hear the filters kick in)
- 3.13 MF toning starts
- Entire MF string is 'KP1' 0 4 4 1 8 3 1 'ST'
- KP1 duration .102 pause until next digit .015
- 0 duration .068 pause .050
- 4 duration .066 pause .052
- 4 duration .067 pause .051
- 1 duration ***.039*** pause .000
I call this the mangled '1' MF digit, because it appears the audio engineer working on this song must have cut and respliced the middle of the MF tones. The duration is very short 0.039 vs. 0.67 and there is no corresponding pause after the digit. It is instead jammed right up to next '8' digit. If you look at the wave you can tell it is a very ugly splice point.