What is the difference between Auto and manual answer?

• Auto Answer is a built–in feature that will receive an incoming fax automatically. With Auto Answer enabled, the unit should receive faxes without user intervention. If Auto Answer is not enabled, the fax will ring only and never answer the phone.
  
  NOTE: If you are able to send a fax but are unable to receive one, Auto Answer may be disabled.
  
  To receive faxes manually, turn off the Auto Answer feature to enable manual answer mode. User intervention is required to answer faxes in this mode:
  1. When your telephone rings, lift the phone off the hook.
  2. Listen to distinguish whether the incoming call is a fax communication or a telephone call.
  3. If the communication is a fax, select Receive on the product's control panel, then press OK.
  4. Press the Start Button.
  5. Replace the phone back on the hook.
  NOTE: You do not need to wait until fax is finished, the fax will hang up automatically.
  Related References
  Receiving Faxes