Came across this site the other day, and hadn't before see everything "official", on one document. I know in the past there always seems to be someone wondering what tone frequencies and cadence should be used on their system, for a specific country/region.
https://www.itu.int/ITU-T/inr/forms/files/tones-0203.pdf
https://www.itu.int/ITU-T/inr/forms/files/tones-0203.pdf
