HA-5231M is a private branch exchange (telephone switching system) that switches calls between VoIP (voice over Internet Protocol or IP) users. It allows the phones to talk to each other by voice and video and provide call detail records. These phones can be an IP phone, software phone, the ICP DAS HA-401, SI-002 and so forth. In addition, we also provide the utility software for users to management the HA-5231M. By using this module, users can manage their SIP phone easier and more flexible.