Complete silence and hangs up after about 30 seconds

Is (02) 9137 2755 a nuisance caller?

answered and was completely silent, i hung up

nuisance.

Get a message saying "Hi all our operators are busy and we will call you back shortly". I believe it's one of those Asian telemarketers hiding behind real Aussie phone numbers.

Cocksucker spammer, apply on seek and start getting 1000s of spam calls

no answer

When answered there is complete silence. I hung up after 15 sec.

silence and hangs up

answered but complete silence

Silence - hangs up shortly

I called back number (02) 9137 2700 reached voice mail but did not say for what company.