VoIP SIP ATA(Analog Terminal Adatper) is a cost-effective product for the VoIP application. User can enjoy the benefit of VoIP to make a international phone call. Using the SIP v1/v2 technology, user can register a phone number via free SIP server on the internet and make a call to the others which have the SIP number too. You don't need a computer to make a call, just use your phone to dial.There are 3 models for VoIP ATA, 1 FXS, 2 FXS or 1 FXS and 1 FXO. Customer can choose the one for their business or market requirement.