You may occasionally see an incoming call labeled "Robocaller (Unblockable)". These calls are likely coming from a robocaller who has spoofed a phone number very close to your own, tricking most call blockers and hoping to fool you into thinking it's a friend or family member.
So why doesn't Nomorobo just block these like other calls?
The reason we can't block these calls outright is that if we put them on Apple's "block" list then they'll be blocked even if they're from a contact in your contacts list. And obviously you don't want calls from actual friends and family members blocked. On the other hand if we only identify these numbers as a "Robocaller (Unblockable)" then Apple does allow your contacts list to override the label and the call will be labeled correctly.
We believe this to be a bug on Apple's part and have told them so, but in the mean time our best solution is to label these calls as "Robocaller (Unblockable)".