The VTG3306A Trunking Gateways is a VoIP gateway with IP-PBX functions, provides 2 FXS and 2 FXO ports. It provides a VoIP solution for saving long distance and international call expenses. By using Edge-Core's VoIP Trunking Gateway, users can keep their original dialing numbers between headquarters and branch offices. There is no need to buy a PBX for newly established branches. PSTN calls between branch offices can be replaced with IP calls which will be free of charge. All international calls to PSTN will be charged as local calls. ROI (return of investment ) is very fast.