To me it sounds like he isn't getting any data. It has been reported by others that they can do voice and texts but not data for several reasons.
Questions:
Are you on the Simple Choice postpaid plan?
What phone do you have? Nexus 5 phones have had tech problems.
Have you enabled roaming data on the phone? Default is usually "no data when roaming".
Some people have to end a #766# code to the system to enable data roaming.
Are you able to do voice and text?