Patent ID: 7672442

Claim:
A signal relay device for bridging a public switched telephone network (PSTN) and an Internet protocol (IP) network, comprising: a master signal relay process module, comprising a first Message Transfer Protocol 3-User Adaptation Layer-Layer Management (M3UA-LM) module corresponding to a communication layer of M3UA and a first Stream Control Transmission Protocol-Layer Management (SCTP-LM) module corresponding to a transmission layer of SCTP, establishing a connection to the IP network; and at least one slave signal relay process module, coupled to the master signal relay process module, comprising a second M3UA-LM module corresponding to the communication layer of M3UA and a second SCTP-LM module corresponding to the transmission layer of SCTP, reestablishing the connection to the IP network when it is broken; wherein the master signal relay process module sends second synchronization data using the first SCTP-LM module when communication data is transferred between a media gate controller and a signal relay device, the slave signal relay process module receives the second synchronization data using the second SCTP-LM module, updating an SCTP database based on the second synchronization data, the first M3UA-LM module sends third synchronization data when the communication data changes service status of the media gateway controller, and the slave signal relay process module receives the third synchronization data using the second M3UA-LM module, updating a M3UA database based on the third synchronization data.