Ok I think I have it. I looked thru the options and found that I had my font size set to 14. Due to the larger size, it took up more of the screen to display the callback number.
I went into Options then Screen/Keyboard and set the font size to 10. This still allows the callback number to be displayed but on 1 line instead of 3 which will give you 4 lines to read the incoming text. If you try try font size 11 or 12, you will see that you lose one more line for reading your text the larger you go.
Let me know how this works out for you.