Missed call no message

I didn't answer as my phone indicated that it was a suspected spam call.
Don't know who it was from as the number doesn't register with the phone number check sites.
Just 4 minutes before this call, I had a call from (08) 7119 7304 also listed as suspected spam, so I left it unanswered. Suspicious that I received 2 phone calls minutes apart, that my phone indicated were suspected spam.

phoned back to get a recorded message advising me to hold the line and the next operator would answer my call