Use the global tone detection mechanism provided by most voice cards to detect tones that may occur during a call, such as incoming fax or busy tone.
These tones are not the result of out-dialling, but tones that may appear during a call. Tones that are expected as a result of dialling are handled by call progress analysis.
Each global tone is assigned a unique ID by the tone learning utility provided by the voice card manufacturer. This tone ID is used to identify the tone when it is received. The global tone ID is stored in the LineGroup controls GlobalTone property.
When a global tone is detected, the system checks for a valid control name in the GlobalToneControl property for the current control. This property can be set using the Connections page.
If a control is set, the call exits the current control and enters the new control. If a designated event handler is not specified, the system checks for a GlobalTone handler in the LineGroup control. If the LineGroup specifies a handler, the call enters that control. If no handler is found in the LineGroup control, the systems terminates the call.
Global tones are defined by the call progress learn utility for your voice card. See Global Tone Detection.
When a global tone is detected while performing call progress analysis as part of a dial operation, the global tone handler is not invoked. Instead, the global tone result is returned in the CallResult property of the Dial control, and the call exits out of the Other node in the Dial control.
To enable or disable Global Tones handling on a channel, it needs to already have a voice resource attached. Enabling and/or disabling Global Tone handling when there is no voice attached (e.g. when a line is in the wait for ring state) will not apply the change in state desired.