IntelliSIP from Voice Carrier is a business phone service that integrates with existing PBX phone systems and allows users to make calls online. Key features include conference calling, auto attendants, interactive voice response (IVR) management, call routing, voicemail to email and more. Users can add or remove calling lines, create personal conference lines, and invite multiple callers to join conference calls or broadcast messages through pre-recorded voicemails. The solution offers a personalized portal for both administrators and users.