(MultiVendor Integration Protocol) A voice bus and switching protocol developed by Natural Microsystems, Natick, MA, and others. Used to build call center equipment using regular PCs, MVIP provides a second communications bus within the computer that can multiplex up to 256 full-duplex voice channels from one voice card to another. Digital voice, fax and video is bussed over a ribbon cable connected at the top of each ISA or PCI card. MVIP products make a PC perform like a small-scale PBX. For example, an interactive voice response (IVR) system on one card can pass incoming voice conversations to a card that switches the lines to call center agents. Several fax boards can be cabled to a board that multiplexes their lines onto a T1 channel.