There is an unknown caller that gets through my DND via FaceTime. I have tried to block to no avail

hey, recently me and my friends have all been receiving constant facetimes and calls from a no caller ID. At first we all thought it was someone in our group playing a prank and calling us but now looking farther into it i don’t think it is. We have each sent screenshots of the missed calls so we know it’s none of us. i’ve even went as far as blocking every number on the call and i’m still getting them. somehow it’s managed to glitch through my do not disturb, as well as separately turning off my facetime notifications. any help or advice greatly appreciated x

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