The phones support SIP, I had purchaced them from SIPPhone.com but their service doesn't work with IPTables NATs, so I had to move over to FWD, And they can dial direct IP addresses, you just pick up the phone, and hit MENU then the IP address padding with leading zeros as needed, and if you need a leading part that's alpha, the manual gives instructions on how to encode it. For your example it would be 100*044130021080.