I'm in Australia and I get recruiter calls all the time. I've said I'm interested to all of them, and then they just stop talking to me. No idea what's going on

I'm in Australia and I get recruiter calls all the time. I've said I'm interested to all of them, and then they just stop talking to me. No idea what's going on. Seems like recruiters are just spamming out first contact messages and then selectively picking the replies they want to respond to.