Data works, but cannot send or recieve texts, calls.

Have a friend whom has asked me to look at her phone as after installing an update, she can no longer make calls or send / receive texts.

Her data however, is working fine and she can browse the internet or use the phone as a hot spot to watch netflix / youtube, etc.

I havn’t been able to get the phone from her to check anything unfortunately, and I have a few ideas, but I havn’t come across this problem before and wouldn’t mind some additional ideas to help me with troubleshooting.