Hey Lobster - check out apple description of Live Voice Mail:
Use Live Voicemail on your iPhone – Apple Support (AU)
"If you don't answer a call while on your carrier network, it's also sent to Live Voicemail."
"When Live Voicemail is on, your phone picks up incoming calls to capture the caller's voicemail for you to see in real-time."
"Your voicemails are never deleted on your behalf"
"If Visual Voicemail is turned on, voicemails captured by your network provider also appear in the Voicemail tab. If your iPhone is turned off or out of your network provider's range, calls go to network provider
voicemail. Otherwise, the call goes to Live Voicemail."
Seems pretty clear to me - under multiple circumstances Apple are recording the caller's audio and calling them Voicemails. People can debate whether Apple will use the audio for other purposes but from my point of view this should never have been on by default. I just realised that I'm breaching my callers privacy by not warning them that Apple is collecting their voice data.