iPhone 8 in Italy not working

There could be a few reasons..

Does he have data roaming turned on?

Is his version of the iphone compatible with Verizon's International plan?

Have you contacted Verizon?

Why don't you go through this page to troubleshoot..

https://www.verizon.com/support/travelpass-faqs/#:~:text=After%20you%20add%20TravelPass%20to,country%20to%20use%20Travel%20Pass.

All of the above, but I would also suggest that he try rebooting his phone to see if that works. That can fix a myriad of problems in many cases.

all of the above and make sure his phone is updated - at least as far as it can be.

Check the roaming settings. More info here:
https://www.verizon.com/support/knowledge-base-207031/

Thank you all for the quick responses! We spoke to Verizon and he got his phone working.