Prior to SBC 8.2, the SBC supported ingress precondition interworking when the ingress side of the call supported precondition attributes, but when the egress side of the call did not.

The SBC is enhanced to send the initial INVITE to the egress when it meets the ingress side preconditions.

 

The SBC sends the P-Early Media (PEM) header as  sendrecv to ingress when it satisfies the following conditions:

  • The SBC invokes the ingress precondition interworking
  • The performPrecondtionRenegotiation flag is in enabled state on the ingress trunk group
  • The SBC supports PEM on the ingress
  • The SBC does not support PEM on the egress
  • The SBC plays either early media or performs end-to-end cut-through

Command Syntax

% set addressContext default zone <zone_name> sipTrunkGroup <siptrunkgroup_ingress_name> signaling performPrecondtionRenegotiation 
<enabled | disabled>

Command Parameters

preferUPDATEOverReINVITE Parameters

ParameterDescription
performPrecondtionRenegotiation

Enable this flag on the ingress trunk group to allow the SBC to renegotiate the precondition on the ingress when there is a change in SDP during early dialog phase or whenever the call goes to confirmed state. The SBC supports this flag for SIP gateway-gateway call.

The options include:

  • disabled
  • enabled

Note:

This flag does not apply when either the dialog transparency flag or the updatedAnswerIn200Ok flag is enabled..

Command Example

% set addressContext default zone ZONE_INGRESS sipTrunkGroup TG_INGRESS signaling performPrecondtionRenegotiation enabled