I may be a bit late to see this chain of thoughts and I would like to leave something for you to think about too.
1. Man vs machine - Yes, with AI growing very fast we may soon be there however, there will still be a minimum requirement of humans to run the show...so competition will increase!!
2. Main concern here - candidates do not appear on their appointed hour-I am sure and am hoping that all interview calls that you organize you also are giving the candidates option to withdraw/communicate of any change with a specific deadline and most importantly you are working with only confirmed in writing of their acceptance of the interview schedule.
Should he/she/they not turn up on their appointed hour - I would put their CV for hold in my repository with a remark of this no-show; and query if need be with him/her/them the reason.
Recruitment is a professional process where it should be a win-win for both organisations and candidates so by trying to chase them, contact them and get no response we tend to see desperate rather than professional as it is up to them to also keep the communication open.
Hope my thoughts help....
From India, Chennai