On the LG smartphone, you can block phone numbers, which automatically rejects calls from these numbers, and no notification of the block is displayed on the LG device.

Android 9 | LG UX 9.0
Block a Phone number -  Open the  Phone -App
Block a Phone number -  Open the  Menu
Block a Phone number -  Tap on  Call settings
Block a Phone number -  Tap on  Call blocking & Decline with message
Block a Phone number -  Tap on  Blocked numbers
Block a Phone number -  Tap on  Add
Block a Phone number -  Choose between  Contacts,   Call logs  and  New number
Block a Phone number -  Enter a  Number  and tap on  Block
  1. Open the Phone-App
  2. Open the Menu
  3. Tap on Call settings
  4. Tap on Call blocking & Decline with message
  5. Tap on Blocked numbers
  6. Tap on Add
  7. Choose between Contacts, Call logs and New number
  8. Enter a Number and tap on Block

LG Instructions
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