Turn on DTMF from Menu-Settings-Call Settings-Send DTMF (option 9). When setting up the phone number in your address book, press and hold # to insert pauses. You should see a 'P' displayed. That said, I can configure my VM to auto enter the PIN, but the phone then immediately stops recognizing DTMFs. I can't even press 1 to listen to messages! This phone has plenty of annoying issues like this and LG doesn't seem to solve any of them.