Very likely a scam call centre.
I’ve had 17 calls in 3 days from numbers with the same first 7 digits. I answered 2 calls and they were silent calls that hung up after a few seconds. A 3rd call I answered and a man said he was cold calling recruiting for an offshore company looking for virtual assistants. He knew my name and was phishing for information.

Constant calls from similar numbers, sometimes within close periods of time. Don't answer these ones. 100% scammers

Blocked by my phone as an Unknown Caller. No message left so assuming it's a spam caller

Multiple calls from similar numbers. Always the same first 6 digits If I answer it’s silent and then hangs up. If I don’t answer, no message left.

Ringing for days! Doesn’t speak when answering