Three-Way Conferencing

The device supports three-way conference calls. Three-way conferencing occurs when an endpoint connected to the FXS port initiates a call and invites two remote IP-based participants. The device also supports multiple, concurrent three-way conference calls.

The feature is applicable only to FXS interfaces.

The device supports the following three-way conference modes:

■ Conference Managed by External AudioCodes Conferencing (Media) Server: The conference-initiating INVITE sent by the device uses the ConferenceID concatenated with a unique identifier as the Request-URI. This same Request-URI is set as the Refer-To header value in the REFER messages that are sent to the two remote parties. To enable this mode, configure the [3WayConferenceMode] parameter to [0] (default.)

To join a conference, the Request-URI includes the Conference ID string preceded by the number of the participants in the conference and terminated by a unique number. INVITE messages with the same URI join the same conference. For example: 

INVITE sip:4conf1234@10.1.10.10
■ Conference Managed by External, Third-party Conferencing Server: Two optional modes of operation:
● The conference-initiating INVITE sent by the device uses only the ConferenceID as the Request-URI. The Conferencing server sets the Contact header of the 200 OK response to the actual unique identifier (Conference URI) to be used by the participants. The device includes this Conference URI in the SIP Refer-To header value in the REFER messages sent by the device to the remote parties. The remote parties join the conference by sending INVITE messages to the Conferencing server using this conference URI. To enable this mode, configure the [3WayConferenceMode] parameter to [1].
● The conference-initiating INVITE sent by the device uses only the ConferenceID as the Request-URI. The Conferencing server sets the Contact header of the 200 OK response to the actual unique identifier (Conference URI) to be used by the participants. The Conference URI is included in the URI of the REFER with a Replaces header sent by the device to the Conferencing server. The Conferencing server then sends an INVITE with a Replaces header to the remote participants. To enable this mode, configure the [3WayConferenceMode] parameter to [3].

When the device is used for Gateway and SBC applications, it can also support conference calls initiated by third-party network entities (e.g., Skype for Business) that use the same Conference server. To support these conference calls, you can do one of the following:

◆ Configure the third-party network entity with a Conference ID that is different from the Conference ID configured for the device.
◆ Configure the device with an Inbound Manipulation rule that is applied to calls received from the third-party network entity so that the device considers conference calls as regular calls and forwards them to the Conference server without getting involved in the conferencing setup.

To join a conference, the Request-URI includes the Conference ID string preceded by the number of the participants in the conference and terminated by a unique number. INVITE messages with the same URI join the same conference. For example: 

INVITE sip:4conf1234@10.1.10.10

Three-way conferencing using an external conference server is applicable only to FXS interfaces.

■ Local, On-board Conferencing: The conference is established on the device without the need for an external Conferencing server. The device supports up to 24 simultaneous, on-board, three-way conference calls. This feature supports local mixing and transcoding of the three-way conferencing legs on the device and multiple codec conference calls. You can configure the maximum number of simultaneous, on-board conferences, using the [MaxInBoardConferenceCalls] parameter.

The device uses resources from DSPs for on-board conferencing calls. However, if there are no available resources from the device's pool of DSPs, the device obtains resources from idle FXS ports to establish the conference call. You can specify ports that you don't want to be used as a resource for conference calls that are initiated by other ports, using the [3WayConfNoneAllocateablePorts] parameter.

To enable this mode, configure the [3WayConferenceMode] parameter to [2].

● Three-way conferencing is applicable only to FXS interfaces.
● Instead of using the flash-hook button to establish a three-way conference call, you can dial a user-defined hook-flash code (e.g., "*1"), configured by the HookFlashCode parameter.
● The device supports high definition, three-way conferencing using wideband codecs (e.g., G.722 and AMR-WB). This allows conference participants to experience wideband voice quality. Call conferences can also include narrowband and wideband participants.

The following example demonstrates three-way conferencing using the device's local, on-board conferencing feature. In the example, telephone "A" connected to the device establishes a three-way conference call with two remote IP phones, "B" and "C":

1. A establishes a regular call with B.
2. A places B on hold, by pressing the telephone's flash-hook button and the number "1" key.
3. A hears a dial tone and then makes a call to C.
4. C answers the call.
5. A establishes a three-way conference call with B and C, by pressing the flash-hook button and the number "3" key.
➢ To configure three-way conferencing:
1. Open the Supplementary Services Settings page (Setup menu > Signaling & Media tab > Gateway folder > DTMF & Supplementary > Supplementary Services Settings).

2. From the 'Enable 3-Way Conference' drop-down list (Enable3WayConference), select Enable.
3. From the '3-Way Conference Mode' drop-down list (3WayConferenceMode), select the three-way conference mode (e.g, On Board).
4. For On Board mode:
● In the 'Max. 3-Way Conference' field (MaxInBoardConferenceCalls), enter the maximum number of simultaneous, on-board three-way conference calls.
● In the 'Non Allocatable Ports' field (3WayConfNoneAllocateablePorts), enter the FXS ports that you don't want to use to obtain resources for conference calls when there are unavailable DSP resources.
5. In the 'Conference ID' field (ConferenceID), enter the Conference Identification string.
6. The valid value is a string of up to 16 characters. The default is "conf".
7. Configure one of the following for how the device recognizes a three-way conference request:
● In the 'Establish Conference Code' field (ConferenceCode), enter the DTMF digit pattern (e.g., hook flash) that upon detection generates the conference call.
● From the 'Flash Keys Sequence Style' drop-down list (FlashKeysSequenceStyle), select Sequence 1 or Sequence 2 to use the flash + 3 key-combination to create the three way conference call.
8. Click Apply and then restart the device with a save-to-flash for your settings to take effect.