The calls were meant to trick Mizuno into "reporting AI problems" to that specific number. Likely the culprit wanted to catch Mizuno's report and attempt to either bury it under the sand or counter with a silent patch. However, Mizuno was actually in contact with the actual committee member (Yukimura), leading him to figure out something suspicious' going on so he dug even deeper, getting too close to discover the loophole so he had to be silenced.I'm kinda confused how receiving prank calls making him think there's a bug in the AI code. Is there a missing page? Who is supposed to be the prank caller?