Block Incoming Calls:

  1. Open the “Apps” drawer
  2. Launch “People
  3. Tap “Menu
  4. Access “Manage contacts” > “Blocked contacts
  5. Tap “+
  6. To block an existing contact, tick the check box next to the contact and tap “Save”. Optionally, tap “OK” to copy the contact information to a different account before blocking
  7. To block a new phone number: enter it and tap “OK” to confirm

Unblock Calls:

  1. Tap “Apps” on the home screen
  2. Open “People” and tap “Menu
  3. Tap “Manage contacts” > “Blocked contacts
  4. Tap “Menu” > “Remove blocked contacts” and select the contacts you wish to unblock
  5. Tap “Delete” to confirm

Block Messages:

  1. Tap “Messages” on the home screen
  2. Tap and hold the message thread exchanged with the number you want to block
  3. Tap “Block contact” in the “Message options” pop-up

Unblock Messages:

  1. Launch “Messages
  2. Tap “Menu
  3. Access “Block list
  4. Select the contact you want to unblock and tap “Menu
  5. Tap “Unblock contacts

Enable Call Forwarding:

  1. Tap “Apps” on the home screen
  2. Access “Settings” and tap “Call
  3. Tap “Call forwarding” and select “Always forward
  4. Enter the phone number you want to forward calls to and tap “Enable

Forward Calls (Conditional Forwarding):

  1. Launch “Settings
  2. Tap “Call” > “Call forwarding
  3. Select to “Forward when busy”, “Forward when unanswered” or “Forward when unreachable
  4. Enter or update the phone number you want to use for call forwarding
  5. Tap “Update” or “Enable

Turn Off Call Forwarding:

  1. Open “Settings
  2. Go to “Call” and tap “Call forwarding
  3. Select “Always forward” or a different forwarding option you want to turn off
  4. Tap “Disable” to confirm

See More: HTC One A9s: Block / Unblock Calls & Messages; Manage Call Forwarding