This support request brought to life what I had seen in the changelog about .wav files for use with PhonePosts.
FAQ 184, titled "How do I play a phone post? What are Ogg Vorbis files (.ogg)?" needs to be tinkered with, as it is now possible for a journal owner to select a form of .wav file instead of OggVorbis. (I'm sorry, it's really late and I have zero for creative juices to fix it right now.)
Going to post a new top-level post for 183, as well, for its related issues.