To improve a deterioration in scalability in a fault and to actualize VOIP network constitution with high reliability.

In a device which determines and manages a trunk termination destination of PBXs (2, 3) whose scalability of termination is to be improved by constructing a termination group with a plurality of VOIP trunks, a VOIP trunk (1-a') of an origination-side PBX (1) is provided with alternative address information for bypassing in the case that a connection with a normally connected device is disabled so as to evade such cases that the trunks in the same termination group become unable to terminate in the case of a failure of connection with the device, thereby enabling a bypass connection with the alternative address. In a preferred example, a general trunk in the group is enabled to terminate, for example, if a VOIP trunk 2-a being a representative trunk of the termination-side PBX 2 cannot be connected because of a fault.