I just got 2 minutes of what sounded like a cross between snoring and farting.
And then line busy, when I tried to call back...

NRL membership drive

Further to my last comment - the number kept calling, when I finally answered it was a recorded message from the Sydney Swans. So, it's a marketing company.

Just had a missed call - I don't have business with Allianz so it's unlikely it's them. I also get a busy signal when trying to return the call. My guess is spam/scam.

I've had several missed calls from them as well but cannot seem to get through on a return call. Seems like it must be spammers or scammers then.