Developer's DescriptionBy Shamrock SoftwareUse a software-based PBX for IP telephones and for ISDN integration.Cactus is a software-based public branch exchange (PBX) for Voice over IP telephones. It runs on any Windows PC with a network adapter and also implements a VoIP-ISDN gateway if an optional ISDN card is plugged into the PC. Cactus is SIP compliant and avoids external IP traffic for internal telephone conversation. For external calls, all SIP-based providers like SipGate can be used.