Name ID + VM bundle, add on

 Hi,  in my family plan, one of my lines has the add  on feature of Voice Mail to text feature; I got it specifically for my hearing impaired family member.  It's  $3.40 p month. 

This way,  if a caller leaves a voice mail message,  it transcribes into text she can read. 

This feature worked fine when she had an android phone. 

Now,  she has the iPhone 11 Pro Max. She got the phone from a private party.

So I don't think the phone came with the visual voice mail app installed. What is the name of the app that will make this feature work? Thanks in advance