Samsung Galaxy S6 User Manual page 49

Block a Number
By adding a caller to your Block list, future calls from
this number are sent directly to your voicemail, and
messages are not received.
1. From a Home screen, tap
2. Tap Recents.
3. Tap the caller you want to add to the Block list.
4. Tap Details > More options > Block number.
Confirm when prompted.
You can also modify the Block list in Settings:
► From a Home screen, tap
More options > Settings > Block numbers.
Calling
Phone.
Phone >
40 Make and Answer Calls