A method of enabling roaming of a mobile internet-access terminal from a first to a second internet access network each of which has a home agent for routing internet datagrams between networks. The method comprises de-registering the mobile terminal from said first network and registering it with said second network and allocating to the mobile terminal a new internet address in said second network. This new internet address is transmitted to the first network's home agent which registers that address as a care-of-address or co-located care-of-address for the mobile host. Datagrams addressed to the new internet address are sent directly to the mobile host via the second network's home agent. Datagrams addressed to a previous internet address of the mobile terminal in said first network are forwarded from that network's home agent to the mobile host, via the second network's home agent.