The method of displacement in a main network based on IP, node in a subnet within a core network based on IP, and terminal to be registered to a sub network in the core network based on IP

摘要

The present invention is a method, a node and a user terminal for roaming in an IP based main network. A node, in a sub-network of said main network receives a registration request from a user terminal belonging to said sub-network, wherein the registration request comprises an unique extension identity. The node is configured to determine whether said unique extension identity belongs to the sub-network of the requesting user terminal. In case said extension identity belongs to another sub-network, the node will request a routing server of the sub-network for an IP-address of a home sub-network for said unique extension identity. The routing server is configured to respond the IP address of the requested home sub-network. The node will transmit the IP address to the requesting user terminal for enabling the transmission of a registration request using the IP address to the home sub-network from said user terminal.