Presence server, session control server, and packet relay system

摘要

The object of the invention is to make communication between users smoother utilizing terminal type information. To achieve the object, a terminal type is specified based upon information in login and information acquired by adding the information to presence information is notified. Besides, terminals of the same type are connected by an SIP server. The selection of the communication means of voice communications and a character chat when communication is started and the specification of a calling terminal at a partner terminal are enabled by adding terminal information to presence information and grasping mutual owned terminals. Detailed status can be grasped based upon presence information of the same name by grasping presence information and terminal information. Further, in the case of a terminal not provided with a presence function, an SIP server also identifies terminal type information by deputy and can also specify a calling terminal.