Ethernet phone. A software construct that usually represents a physical telephone instrument, although it is also used to represent a port that connects to a voice-mail system. The ephone construct provides the ability to configure the physical instrument using Cisco IOS software. Each ephone can have multiple extensions associated with it in a many-to-many relationship, and a single extension can be associated with multiple ephones so that it appears as a shared extension. The maximum number of ephones in a Cisco CME system is the maximum number of physical instruments that can be connected to the system.