A scammer has been harassing me for several days, being rude and making fraudulent claims. How can I stop them from calling me?
In your Phone app → Recents, tap the ⓘ next to the phone number you wish to block, then tap Block this Call at the very bottom.
You can also tap the ⓘ next to an undesirable voicemail message under Phone → Voicemail.
Blocked callers can still leave you voicemails, but they will go straight into a separate Blocked Messages voice mailbox without raising a notification or ringtone. You’ll never have to listen to them.
You may also try downloading some call-filtering apps from the App Store. Free ones include Whoscall, Truecaller, and Hiya. They use Apple’s CallKit to proactively block known spammers and scammers. I am not affiliated with any of those apps.
AT&T also offers AT&T Call Protect for its own customers, also on the App Store. Other carriers have their own offerings as well.