Caller: Asian call centre

One of a bunch of numbers that has been calling a couple of times every hour over the last few days: 0488 805 781 - 0488 859 020 - 0488 858 475 - 048885501 - 0488 855 013 - 0488 859 600. Usually they hang up within four rings but a couple of times it has gone to a call desk and I heard something muttered like ... Jar-He-Kwa ... with others talking in the background. Now how do you block numbers on a flip phone?

I got 2 calls from this number as well as 3 others starting in 0488 all in a span of 5 hours they leave a message with nothing you can hear background noise but they don’t say anything