A multilayer piezoelectric generator is disclosed comprising a round, rectangular or other shaped box having a cover. The congested device notifies call connection data passing through it to a PDSN, the PDSN finds the IP address of the terminal using the target connection, and notifies a CSCF as a restriction target terminal. A VID is determined based at least in part on an identifier of a wireless network included in the wireless header, and the VID is assigned to the data unit.