Called three days in a row and then twice in 10 minutes, but never leaves a message and hangs up if you pick up

Same here. I've since blocked the number

Same , called then I did not answer

Autodialers and Mass Calling:
Scammers and telemarketers use autodialers to make a large number of calls quickly.
Identifying Responsive Numbers:
When you answer, the autodialer might switch to a live person, and the scammer can then mark your number as someone who answers unknown calls.
Future Scam Attempts:
Knowing you answer unknown calls makes you a potential target for future scam attempts.
"Neighbor Spoofing" and Other Tactics:
Scammers may use techniques like "neighbor spoofing" (making the caller ID look like a local number) to trick you into answering.
One-Ring Scam:
Some scammers will make a call and hang up immediately, hoping you'll call them back, potentially incurring charges or giving them more information.
Scammers Mark You Down:
When you answer, they know they have a live person on the other end and can mark you down for future scam attempts.
Protect Yourself:
Consider using call blocking apps or services, and be cautious about answering calls from unknown numbers.

Called so many times on my phone but didn’t leave any message.s. When I called back, there is background noise but no answer.

Weird background sounds left as voicemail. When I look at my call history it isn't registered as a call, but message has been left as call has been missed??

Voicemail left with typing noise in background, no identifying voice or email received.

Spam

No msg left- spammer

Mobile flags as spam. No voicemail left. Regard as spam. Number blocked.