Hosted telephony. Access to low-cost and free IP calling, a hosted system provides you with almost unlimited call features with little or no upfront cost.
The Session Initiation Protocol (SIP) is a communications protocol for signaling and controlling multimedia communication sessions. SIP is expected to completely replace ISDN over the next 5-7 years. SIP lines can be activated and deactivated instantly giving customers greater flexibility with their voice and data requirements.