Feature F-5362 'Support of SIP 182 Queued' adds the functionality to process a SIP 182 Queued message if it receives the message from a SIP entity within the network. During call setup, the 182 Queued call status message is sent from the SIP entity to the IMG to notify it that the called party is unavailable at that moment and rather than reject the call, it has been put into a queue and is awaiting for the called party to become available. The IMG then will take the proper actions to either just put call on hold awaiting instructions or to put the call on hold but initiate a connection from IMG to calling party. The latter can be used to relay information to the calling party with an announcement informing them they are in a queue and the call will be answered in the sequence that it came in. Once the called party is available the far end SIP Entity informs the IMG the call can now be connected. The IMG then connects the call from the calling party to the far end SIP Entity.
Note: If PRACK is enabled in SIP SDP then IMG will respond with Provisional Acks as shown in call flow below
Click on F-5319 Call Trace link
There is no extra configuration needed to enable the 182 Queued call status functionality. The SIP 182 Queued message is coded to function automatically when receiving the 182 Queued message.
IMG receives a 182 Queued message with SDP and is first 18x message received. | IMG will cut through media from outbound SIP side to inbound TDM side. This will allow media such as ringback or announcements to be sent from SIP side to TDM side |
IMG receives a 182 Queued message without SDP and is first 18x message received. | IMG will send an Alerting message to the inbound TDM side. Call will stay active in IMG but media will not be cut through |
IMG receives a second 182 Queued message with SDP. At this point the first 182 queued message already cut through media. |
The second 182 Queued message will be ignored. |
IMG receives a second 182 Queued message without SDP. At this point the first 182 queued message already cut through media. | The second 182 Queued message will be ignored. |
IMG receives a second 182 Queued message with SDP. At this point the first 182 queued message was without SDP and no media was initially cut through. | The second 182 Queued message which contains SDP will cut through media to ingress TDM side. |
Due to limitations of the IMG, 180 Ringing after a 182 Queued will not change IMG to play ringback.
If call is a SIP to SIP transcoding scenario and the IMG receives a 182 Queued message, the IMG will generate a 180 or 183 response to the incoming side.
The interworking procedure shall be the same. Alerting/Cut Through is sent due to 180/183 being received. Called Party status of Backward Call Indicator in ACM will be No Indication based on RFC 3398