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Modified: for 6.2.2

Use this object to configure Early Media support for a SIP trunk group.

To View and Edit Early Media

On the SBC main screen, go to Configuration > System Provisioning > Category: Trunk Provisioning > Trunk Group > SIP Trunk Group > SIP Trunk Advanced > SIP Trunk - Media - Advanced > Early Media. The Early Media window is displayed.

Use the drop-down boxes to select the desired Address Context, Zone and SIP Trunk Group. The Edit Early Media window is displayed.

Figure : Sip Trunk Advanced - SIP Trunk Media Advanced Early Media

The following fields are displayed:

Table : Media - Early Media Parameters




 Method used to provide early media.

  • P Early Media– P-Early-Media header value is used for selection the RTP streams.
    • Default Gating Method – Select an option to specify the cut-through method if p-early-media header is   not received from peer.
      • Inactive
      • Recvonly
      • Sendonly
      • Sendrecv (default)
    • Egress Support - Use this flag to include PEM=supported message in the egress INVITE.
      • Disabled - Egress INVITE does not include PEM=supported message regardless of the presence/absence of PEM in the ingress INVITE.
      • Enabled (default) – Egress INVITE includes PEM=supported message regardless of the presence/absence of the PEM in the ingress INVITE.
  • Rtp Server Table – Enter an RTP Server Table name to specify the RTP server profile. This option uses RTP Server Profile to determine whether early media is enabled. If the c-line of the session description matches an   entry in the RTP profile, early media is allowed. RTP Server Profiles are configured per Address Context. One RTP Server Profile is tied to a single Early Media Profile if this option is selected.
  • Session Answer (default) – Use this option for media cut-through on receipt of session answer.

Forking Behaviour

 Use this parameter to identify the method to provide early dialog media selection.
  • First Prov Response – First Reliable Provisional response. Cut through for first provisional response and suppress the rest until final response is received.
  • First Rtp – When this option is selected, the SBC's selection of provisional response for cut-through is determined by the arrival of media packets corresponding to that provisional response. Select this option and set Dynamic LRBT flag to 'enabled' when forking is enabled. With First Rtp enabled, forking behavior is the last provisional response until 180 is received. If First Rtp is enabled, but Dynamic LRBT flag is disabled, forking behavior defaults to the last provisional response
  • Last Received SDP (default) –  Cut through is based on the latest SDP received.
  • Pem Priority – PEM (P-Early-Media) based. Cut through occurs based on the value of the PEM header (default value is sendrecv if not configured).

Make the required changes and click Save.