Call deflection is a feature of voice over IP (VoIP) that automatically redirects a call from the called endpoint to another endpoint (usually a voice mailbox) when the called endpoint is busy. Call deflection is one of several forms of call diversion (also known as call forwarding) defined under the H.450.3 specification.
In call deflection, there are three communications points, referred to as the originating gateway (the point from which the call is made), the deflecting gateway (the called endpoint), and the deflected-to gateway (the ultimate endpoint). Calls are deflected by a command called the reroute invoke. VoIP call deflection may not work for calls originating under other protocols or from all types of communications interfaces. For example, in a Cisco gateway, only calls in H.323 protocol are deflected.