SIP (Session Initiation Protocol)
Internationally recognized IP telephony signaling protocol used for VoIP. This is the most widely used protocol in the market and is a standard meaning anybody who builds a SIP 2.0 compliant product should work with any other SIP 2.0 compliant device. For instance our xBlue SIP module is compliant so any off the shelf SIP phone will work as an endpoint for a home phone or a remote worker. The trick with SIP 2.0 is that the combined devices will work to the feature set of the lowest common denominator meaning a SIP 2.0 telephone only support 80% of the SIP feature set then even though the telephone system supports a higher set of features, you will only have the base features of the phone.

VoIP (Voice over Internet Protocol)
This is simply the carrying of voice via IP meaning a standard voice stream is broken into packets at the transmit end, sent over a standard data network (such as the Internet) and reassembled into a voice stream at the receiving end. VoIP traffic is trickier than normal data traffic because the timing of packets on the receiving end is critical. For more detail see Basics of the Internet.