From  SBC 08.02.01 onwards, to comply with RFC 6337 standards, the flag  onlySendSubsequent18xSdpIfUnreliable is enabled to allow the SBC to include the SDP in subsequent 18x response message after a unreliable provisional response is sent.

Command Syntax

% set addressContext default zone <zone_name> sipTrunkGroup <siptrunkgroup_name> signaling onlySendSubsequent18xSdpIfUnreliable <enabled | disabled>

Command Parameters

onlySendSubsequent18xSdpIfUnreliable

ParameterDescription
onlySendSubsequent18xSdpIfUnreliable

Enable this flag to allow the SBC to send SDP in subsequent unreliable 18x messages. Once the reliable response is sent, the SBC stops sending the SDPs. This behavior is RFC 6377 compliant.

When disabled, the SBC sends the SDP in subsequent 18x messages, regardless of their reliability. This is the same behaviour as releases prior to 8.2.0

For more information, refer to Ingress IP Attributes - SIP - CLI

The options include:

  • disabled (default)
  • enabled

Command Example

% set addressContext default zone ZONE_INGRESS sipTrunkGroup TG_INGRESS signaling onlySendSubsequent18xSdpIfUnreliable enabled