In Tricentis Tosca, about random expressions

I am working on an website in which I have to automate it so, I created an test step, in which I used 2 "random expressions" - 1. phone number and 2. Email....But In another test step I have to verify them whether the phone number and email are displaying or not. My doubt is like how can we verify them if they change every time we run the test case??

Thank you.