The SBC re-initiates the precondition procedure whenever the ingress side Session Description Protocol (SDP) changes due to an 18x/200 OK or UPDATE received from the egress side. The SBC uses this UPDATE message before sending 200 OK to INVITE towards ingress instead of using the RE-INVITE message.
Enable the preferUPDATEOverReINVITE
parameter to use UPDATE instead of Re-INVITE on the ingress to communicate SDP when the call transitions to the confirmed state.
% set addressContext default zone <zone_name> sipTrunkGroup <siptrunkgroup_name> signaling preferUPDATEOverReINVITE <enabled | disabled>
% set addressContext default zone ZONE_INGRESS sipTrunkGroup TG_INGRESS signaling preferUPDATEOverReINVITE enabled