The term used for LAN-attached telephony systems and the associated telephone handsets (that is, the IP version of the PBX). More specifically, IP telephony involves the delivery of the telephony application (for example, call setup and teardown, and telephony features) over IP, instead of using circuit-switched or other modalities. IP telephony is not the same as VoIP or Internet telephony, although the terms are commonly (and erroneously) used interchangeably. See also Internet telephony and VoIP.