Yeap, no dial up and no waiting. In the technical side, I-Mode is a packet switching technology. Well, in short, a telephone call is a circuit switching. That means you own a circuit when you are calling, and you keep the connection for your self. Packet switching on the hand is like IP traffic.
Many users share the media link.
Anyone has the same access right to send a packet. The packet switching allows more users to share the network. One drawback is packet switching cannot provide quality of service. This number sounds low, but it is sufficient for mostly text I-Mode formatted websites. In the near future, DoCoMo is planning to have 3G network, 3rd Generation network.