Event Detection and Notification using X-Detect Header

The device can detect certain events in the media stream and notify of their detection to a remote application server, using the SIP X-Detect header. The request for event notification is done by the application server when establishing a SIP dialog (i.e., INVITE message) or during an already established call using a re-INVITE message. The device can detect the following event types:

■

Answering Machine Detection (AMD): Detects events that are related to the AMD feature. AMD detects whether an answering machine or live voice has answered the call. It can also be used to detect silence, or the beep sound played by an answering machine to indicate the end of the greeting message after which a voice message can be left. For more information on AMD, see Answering Machine Detection (AMD).

■

Call Progress Tone (CPT): Detects whether a specific tone, defined in the installed CPT file is received from the call. It can be used to detect the beep sound played by an answering machine (as mentioned above), Special Information Tones (SIT) which indicate call failure with a recorded announcement describing the call failure (Gateway application only), and the busy, reorder and ring tones.

■

(Gateway application only) Fax/modem machine: Detects whether a fax has answered the call (preamble, CED, CNG, and modem).

■

(Gateway application only) PTT : Detects the start and end of voice.

The X-Detect header is used for event detection as follows:

■

X-Detect header in the INVITE message received from the application server requesting a specific event detection:

X-Detect: Request=[event type to detect]

■

X-Detect header in the SIP response message -- SIP 183 (for early dialogs) or 200 OK (for confirmed dialogs) -- sent by the device to the application server specifying which of the requested events it can detect (absence of the X-Detect header indicates that the device cannot detect any of the events):

X-Detect: Response=[supported event types]

■

Each time the device detects the supported event, it sends an INFO message to the remote party with the following message body:

Content-Type: Application/X-Detect
Type = [event type]
Subtype = [subtype of each event type]

The table below lists the event types and subtypes that can be detected by the device. The text shown in the table are the strings used in the X-Detect header. The table also provides a summary of the required configuration.

For SBC calls, event detection is enabled using the IP Profile parameter 'Handle X-Detect' (see Configuring IP Profiles).

Supported X-Detect Event Types

Event Type	Subtype	Description and Required Configuration
AMD	■ Voice (live voice) ■ Automata (answering machine) ■ Silence (no voice) ■ Unknown ■ Beep (greeting message of answering machine)	Event detection using the AMD feature. For more information, see Answering Machine Detection (AMD).
CPT	■ SIT-NC ■ SIT-IC ■ SIT-VC ■ SIT-RO ■ Busy ■ Reorder ■ Ringtone ■ Beep (greeting message of answering message)	Event detection of tones using the CPT file. 1. Create a CPT file with the required tone types of the events that you want to detect. 2. Install the CPT file on the device. 3. For SIT detection: ✔ Set the SITDetectorEnable parameter to 1. ✔ Set the UserDefinedToneDetectorEnable parameter to 1. Note: ■ For more information on SIT detection, see SIT Event Detection. ■ To configure beep detection, see Detecting Answering Machine Beep.
FAX	CED	■ Set the IsFaxUsed parameter to any value other than 0. - or - ■ Set the IsFaxUsed parameter to 0 and the FaxTransportMode parameter to any value other than 0. Note: Applicable only to the Gateway application.
	modem	Set the VxxModemTransportType parameter to 3. Note: Applicable only to the Gateway application.
PTT	■ voice-start ■ voice-end	Set the EnableDSPIPMDetectors parameter to 1.