I don't know if it can be "added" to the phone, but my wife and I both got new phones, the Env2 and it has Visual Voice Mail already on the phone. Just have to set it up, but I'm not going to pay an extra $2.99 a month just to have it.
"The Marines I have seen around the world have, the cleanest bodies, the filthiest minds, the highest morale, and the lowest morals of any group of animals I have ever seen. Thank God for the United States Marine Corps. Eleanor Roosevelt, 1945"