Avoid unwanted calls on iPhone
You can avoid unwanted calls by blocking certain people and sending unknown and spam callers directly to voicemail.
Block voice calls, FaceTime calls, and messages from certain people
In the Phone app , do any of the following.
Tap Favorites, Recents, or Voicemail. Tap
next to the number or contact you want to block, scroll down, then tap Block this Caller.
Tap Contacts, tap the contact you want to block, scroll down, then tap Block this Caller.
Manage your blocked contacts
Go to Settings
> Phone > Blocked Contacts.
Tap Edit.
Send unknown and spam callers to voicemail
Go to Settings > Phone, then tap any of the following:
Silence Unknown Callers: You get notifications for calls from people in your contacts, recent outgoing calls, and Siri Suggestions.
Call Blocking & Identification: Turn on Silence Junk Callers (available with certain carriers) to silence calls identified by your carrier as potential spam or fraud.