I remember an effect (can't seem to remember from where...) in which the magician lets the spectator/s choose 10 random digits which form a phone number, and when they call the magician's phone gets the call. Is anyone aware of an app, product, or book that contains a method for this amazing effect? this can be used for many routines and I think it's a strong one (since I want to honor the forum's restrictions you don't have to mention any detailed methods here)

Toxic? With a calculator

Numbers are freely chosen, no calculator used... he somehow pulled off a result like in The Stranger app but on spectator's phone...

Penguin magic had one. Its a very old method. It would be great if you could find out who.

Cardistry master you don't know by who it was?

I think its this one. https://www.penguinmagic.com/p/14511 that's what I was thinking of but don't know if its the same one you were.