Abstract: A group communications switching method is disclosed. The method includes the steps of: maintaining a voice call between a first subscriber terminal and a second subscriber terminal when it becomes necessary to perform group communications while the voice call is in progress; starting a group communications call by the first subscriber terminal so as to call at least a group communications member other than the first subscriber terminal and the second subscriber terminal; and disconnecting the voice call between the first subscriber terminal and the second subscriber terminal when the group communications call is established.

Abstract: A group communications switching method is disclosed. The method includes the steps of: maintaining a voice call between a first subscriber terminal and a second subscriber terminal when it becomes necessary to perform group communications while the voice call is in progress; starting a group communications call by the first subscriber terminal so as to call at least a group communications member other than the first subscriber terminal and the second subscriber terminal; and disconnecting the voice call between the first subscriber terminal and the second subscriber terminal when the group communications call is established.

Abstract: In a disaster system control method and apparatus transmitting disaster status information through a mobile communication network or a fixed communication network, in order to promptly transmit/receive disaster status information at a time of a disaster occurrence between a disaster monitoring person and afflicted people within a disaster occurrence area, a bandwidth control apparatus assigns a bandwidth for a packet call in preference to other calls, a mobile terminal installs an application for disaster thereon for transmitting/receiving disaster status information between a disaster system center and the mobile terminal itself, and the disaster system center provides the mobile terminal within a disaster occurrence area with an application for disaster startup mail to start up the application for disaster.

Abstract: A system for delivering a caller's phone number to a called subscriber in an Internet telephony system. A calling subscriber (caller) first makes a call to its local server (caller-side server) to request an Internet-based call connection to a remote subscriber (callee). A first transmission unit, disposed in a caller-side local switch, transmits the caller's phone number to the caller-side server through a first control channel. A second transmission unit disposed in the caller-side server then transmits, over the Internet, the caller's phone number to another server (caller-side server) that is local to the callee. The caller's phone number is now available in the callee-side server. A caller number acquisition unit, disposed in the callee-side local switch, makes access to that information by using a second control channel. In this way, the callee-side local switch obtains the phone number of the caller.