Rang while i was busy but no message

As stated below, I didn’t answer the call, no voicemail. Tried to call back and it went straight to voicemail saying “Optus advises that the mobile number you have called has been disconnected” even though it’s a landline? Been getting a ton of random spam calls from Melbourne today, over it

Consistent calling

Spam

Called briefly, did not answer. No message.

No message left, probably spam