Patent ID: 7724752

Claim:
A communication system across networks used in an environment with a public network and a private network, the system comprising: a client end, which is in the public network for transmitting a controlling message; a mobile end, which is in the private network and includes: a preprocessing module for transmitting a connection request; and a controlling module for receiving the controlling message and executing it to return at least one data message; a network service end, which is in the public network and simultaneously connected with the public and private networks, has a conversion table to record the correspondence relation between network identification (ID) codes of the network service end and the mobile end, and transfers packets according to the conversion table; and a server end, which is in the public network, initializes a first socket port and a second socket port when it starts, and includes: a storing module, which stores a correspondence table containing at least the correspondence between a client socket port and a converted socket port; a receiving module, which in the public network receives the controlling message transmitted from the client end via the first socket port and receives the connection request and the data message transmitted from the mobile end via the second socket port; a connecting module, which establishes a connection between the server end and the mobile end according to the connection request and, after the connection is established, records the converted socket port in the correspondence table, and establishes a connection between the server end and the client end according to the controlling message and, after the connection is established, records the client socket port in the correspondence table; and a transferring module, which transfers the controlling message via the second socket port to the mobile end according to the correspondence table and transfers the data message via the first socket port to the client end; wherein the connection between the server end and the mobile end is achieved via the network service end.