Left message (computer, robotic, female) stating our internet connection is compromised and we need to either press 1 for Telstra or 2 for other service provider.

Definitely a scammer.

Just, yet another idiot trying to scam people, these foreign pests need to be exported to whence they came from URGENTLY.......

Left a message on our voicemail say our phone had been compromised and to call this no. We deleted this no. as our phone is working perfectly.

3 missed calls from this number, one of them left a partial computer generated voice message that our internet was being cut off today due to "a compromised line". Clearly a scam.

Call taken by answering machine @ 12:42 pm today. Female voice, American accent.
"Because your line is being compromised from Melbourne from the exchange
Press 1 for Telstra support. Press 2 for other provider." Sounds like bait for some sort of scam.

A caller from this number purported to be from "Telstra Internet Service", telling me there had been a temporary problem with my service that needed to be repaired. As I don't have Telstra Internet, I told him what I thought of his call and hung up!!