A PBX that has both TDM and IP components co-existing, side-by-side. The TDM component comprises TDM line and trunk cards and ports and a TDM bus. The IP component comprises Ethernet ports, an Ethernet switch, a router, and IP trunk ports. A gateway interconnects the TDM and IP components, both of which are under the control of a telephony server running a commercial operating system (OS). See also IPBX.