They have called a few times in the last couple of weeks and keeps coming up as suspected spam. If it was something important I figure that they would leave a msg...but they don't and that's what concerns me.

Seemingly yet another scam call, two from similar numbers now: (02) 9184 7009 and (02) 9184 7172. They phone and then hang up without leaving a message - the usual thing.

Called then hung up. After reading above comment, suspect it is a spam call.

Same here, and if they don't leave message I block the number.