If 125207 is “Hi”, and 031993121212 is “Dude”, then 125207031993121212 is “Hi Dude”.
Then what is
799717777010909230151693122001983?

Answer
It’s “You Are Great”.
Separate the numbers into groups of three, and then add up the three numbers. The total amount will point to a certain letter, and if you continue doing it until all numbers are used, it’ll form the sentence “You Are Great”.