Send audio file via Andoid phone call without internet

I have 2 Android phone (I can be rooted on them) . I can write on each of them Application. But I have no internet for those phone.

I want to send audio file from 1 phone to another via phone call and that audio file will be binary same.

I know that in phone there is audio encoder that may change the data (encoding/pack/compress data) can I skip on this module so I can send audio file via phone call that will be exactly same binary?

from Send audio file via Andoid phone call without internet