Live Call Routing - IVR customization

Currently there is no way to customize 90% of the IVR and robo-voice that the user experiences when they call into a Live Call Routing number. Even if you upload a silent MP3 file to the Greeting section, there is still a Pagerduty-provided robot voice that makes multiple announcements, with no way to suppress or customize them.
Additionally, we’d like to suppress the “trying next responder” announcement, or add hold music, neither of which seems to be possible.