1. Configuration Guide
  2. SIP Signaling Services
  3. Early Media Support
  4. Early Media Support for Multiple Early Dialog Scenarios

Early Media Support for Multiple Early Dialog Scenarios

By default, the ESBC supports the P-Early-Media (PEM) header for authorizing early media, and multiple early dialogs with PEM headers. With additional configuration, it can expand on early media support functions related to multiple early dialogs and PEM header management that target specific environments or deployments, such as SIP/SIPI interworking and access VoLTE deployments.

Specific configurable early media support functions include:

  • Hiding the multiple early dialogs by merging them into a single dialog when deployed in a SIP/SIPI environment. With some legacy equipment (MGCs, PBXs), this becomes necessary because SIP-I does not support multiple early dialog
  • Resolution and collation of many-to-many dialog scenarios
  • Mapping a SIP UPDATE towards the right early dialog when deployed within an access VoLTE environment
  • Appropriate media latching when presented with multiple latching choices

Configuration of these enhanced multiple early dialog support, including PEM header, dialog merging, and many-to-many dialog support includes:

  • Set the sip-config option multiple-dialogs-enhancement. By default this option is not configured.
  • In the realm-config, enable the merge-early-dialogs parameter on the caller side to merge early media dialogs.
  • In addition, you can set the p-early-media-header configuration in sip-interface to support to trigger behavior that supports merged early dialogs.

All of this configuration supports real-time configuration, not requiring a reboot.

Note:

The ESBC uses its interaction with the PCRF, via the SIP-Forking-Indication AVP, to reserve the highest QoS requested for that media component by any forked responses. This does not require configuration.

Related Feature Dependencies

The complexity of these enhancements and their related functions can conflict, supercede or depend on other aspects of your ESBC configuration. Configuration dependencies include:

  • The realm-config must have:
    • hide-egress-media-update enabled to maintain RTP consistency
    • A codec-policy set (xcoding enabled)
  • The sip-config must have the multiple-dialogs-enhancement option enabled.
  • If the media-manager has latching enabled, sdp-restrict is disabled.
  • You must not set the dont-save-early-dialog-sdp option.

Recall that the ESBC requires the 100-rel-interworking option set on the ingress sip-interface to support PRACK interworking, which is needed for early dialog support.

Note:

Legacy SDP management (SCz7.2.0 and below) uses the last SDP seen as the source for SDP. You can enable this legacy behavior by setting the dont-save-early-dialog-sdp option in the sip-config. Do not use this unless directed by Oracle. 
ORACLE(sip-config)# options +dont-save-early-dialog-sdp