Probably a predictive dialer. They use these to work out which numbers are 'live', and then follow up with the scam/spam call later.

Called, no message left. Have also received calls this month from:

(07) 2809 3430
(07) 2809 3431
(07) 2809 3432
(07) 2809 3433
(07) 2809 3435
(07) 2809 3436

Usual odd looking interstellar number = suspect. Female voice tried to say “hi” when I told her she had phoned security. Instantly hung up. I doubt this is a mis-dial number, very similar to other numbers with last few digits changed. Blocked

Caller: All Kind Fundraising Centre

These numbers are from an organisation called 'All Kind' Fundraising Centre.... most questionable and unfortunately persistent!

Female voice just says "Hello", & hangs up.
Also from 072083495

Another number that has rung me with no message, blocking

Rang at 2.39am robo caller

Answered but no one was on the line.

Getting calls from 07 numbers regularly. These are typical of most scammer tactics. I never answer unknown numbers and block anyone who doesn't leave a voicemail.

Didn't know the number - Didn't answer - no message left !

Called, no message left.

Same number as previous comment two days later. No message so unlikely to be a mis-dial.

Hung on long enough to get outgoing message but left none. Pest or mis-dial?