Detecting Answering Machine Beeps

The device can detect the "beep" sound played by an answering machine that indicates the end of the answering machine's greeting message. This is useful in that the device can then notify, for example, a third-party, application server that it can now leave a voice message on the answering machine. The device supports the following methods for detecting and reporting beeps:

AMD-based Detection: The device uses its beep detector that is integrated in the AMD feature. You can configure the beep detection timeout and beep detection sensitivity level (for more information, see Configuring AMD). To enable the AMD beep detection, the received INVITE message must contain an X-Detect header with the value "Request=AMD",
X-Detect: Request=AMD

and the [AMDBeepDetectionMode] parameter must be configured to [1] or [2]. If configured to [1], the beep is detected only after the answering machine is detected. If configured to [2], the beep is detected even if the answering machine was not detected.

Tone-based Detection (Call Progress Tone): The device detects the beep according to a call progress tone (CPT). This is enabled if the device receives a specific beep tone (Tone Type #46) that is also defined in the installed CPT file and the received INVITE message contains an X-Detect header with the value "Request=CPT":
X-Detect: Request=CPT

For more information on the CPT file, see Call Progress Tones File.

The device reports beep detections to application servers, by sending a SIP INFO message that contains a body with one of the following values, depending on the method used for detecting the beep:

AMD-detected Beep:
Type= AMD
SubType= Beep
CPT-detected Beep:
Type= CPT
SubType=Beep