I don't know about your FIL, but that suits me just fine. If it's important for my kids to tell me something, they can send an email or show up in person so I can lip-read, because trying to say anything complicated over the phone isn't going to work at all, given their voice ranges.
I won't be seeking treatment. ;)
/johnny
Oh he couldn’t hear me (and most other people) even in person, as far a phone calls I wouldn’t even try because I knew he couldn’t hear. Bbut he would call me and ask for something and I could yell YES loud enough to let him know I would do what he wanted. He wouldn’t have had a clue about email. It was so sad to see him isolated by his lack of hearing. He would sometimes pretend to hear with occasional hilarious results. He was a darling man and we loved him.