7.2.2 BSS Initiated

23.2843GPPLocal Call Local Switch (LCLS)Release 17Stage 2TS

7.2.2.1 Principles

When the BSS determines that local switching should be disconnected it may:

– immediately break local switching and then inform the Core Network, or

– first request the Core Network to prepare for LCLS break and on the reception of LCLS break request on both call legs the BSS breaks local switching.

7.2.2.2 Immediate LCLS break

7.2.2.2.1 BSS actions

When the BSS determines that local switching should be disconnected it shall immediately break local switching. The BSS shall report the LCLS disconnection by sending the LCLS-Notification message with the LCLS-BSS-Status IE set to "the call is no longer locally switched" to both MSC servers associated to the LCLS call.

7.2.2.2.2 MSC server actions

At reception of the LCLS-Notification message with the LCLS-BSS-Status IE set to "the call is no longer locally switched", the MSC server shall send to the succeeding (or preceding) node the LCLS Status Update message with the LCLS-Status IE set to "LCLS Not Connected" if the same LCLS Status Update message was not already received from the succeeding (or preceding) node. If in the related MGW the access side termination is isolated from the network side termination, the MSC Server shall request the MGW to through-connect the access side termination to the network side termination.

7.2.2.2.3 GMSC server actions

On receipt of the LCLS Status Update message with the LCLS-Status IE set to "LCLS Not Connected" from the preceding (or succeeding) node:

– the GMSC Server shall forward the message to the succeeding (or preceding) node if the same request was not already received from the succeeding (or preceding) node.

– the GMSC Server shall not forward the message if the same request was already received from the succeeding (or preceding) node.

7.2.2.3 BSS Requesting LCLS Release from Core Network

7.2.2.3.1 BSS actions

When the BSS determines that local switching should be disconnected but the LCLS release should be ordered from the Core Network the BSS shall request the LCLS disconnection by sending the LCLS-Notification message with a LCLS-Break-Request IE to both MSC servers associated to the LCLS call.

On receipt of the LCLS-Connect-Control message with the LCLS-Connection-Status-Control IE set to "Release LCLS" the BSS shall apply the procedure described in clause 7.2.1.4.

7.2.2.3.2 MSC server actions

At reception of the LCLS-Notification message with LCLS-Break-Request IE the MSC server shall send to the succeeding (or preceding) node the LCLS Status Change Request message with the LCLS-Status-Change IE set to "LCLS-Disconnection-Preparation". If in the related MGW the access side termination is isolated from the network side termination, the MSC Server shall request the MGW to through-connect the access side termination to the network side termination.

On the reception of the LCLS Status Change Request message with the LCLS-Status-Change IE indicating LCLS disconnection preparation, the MSC server shall apply the procedure described in clause 7.2.1.2 with the following exception:

– on the reception of the LCLS Status Change Request Acknowledge message with the LCLS-Status-Change IE set to "LCLS-Disconnection-Preparation" and a Result code IE indicating LCLS Status Change Request accepted the MSC server shall not request the LCLS break if it already requested due to the reception of the LCLS Status Change Request message from the succeeding (or preceding) node.

7.2.2.3.3 GMSC server actions

The GMSC server shall perform the same actions as described in clause 7.2.1.3.