The PLANET VIP-281GS VoIP GSM Gateway is a signal-GSM channel gateway that supports SIP and H.323 VoIP protocol at the same time. The VIP-281GS provides a total solution for integrating voice-data network and the Global System for Mobile Communications (GSM). The VIP-281GS is equipped with both FXS and PSTN interfaces, which gives the gateway a wide range of potential applications. The VIP-281GS can be installed on a PBX trunk line to enrich its trunks-GSM and VoIP routes. The PBX is able to have voice communication to either VoIP or GSM environment by the least costs.