Open the Phone app
Tap the menu or More icon
Go to Settings
Tap Blocked numbers or Blocked contacts
Review the list of blocked phone numbers
On iPhone, open Settings
Tap Phone
Tap Blocked Contacts
Review the blocked numbers list
On some Android phones, open the Messages app
Tap the menu or More icon
Go to Spam and blocked
View blocked numbers there
Check your carrier account or app if blocking is managed by your carrier