14.6.1 General

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

Tones or announcements may be applied at any time during the call establishment or mid-call. Also periodic tones may be applied during the call. Prior to answer, an LCLS compatible call is still connected through the core network and so any tones or announcements applied at this time are handled as for normal non-LCLS calls.

If a node wishes to apply periodic tones during the call it may either reject the LCLS entirely or may indicate that it requires send access in a certain direction. This is achieved during the LCLS negotiation phase as described in clause 4.2.

If the call is established and local switching is performed and at a later point in the call a (G)MSC Server needs to send a tone or announcement there are two options it may apply:

– perform a (G)MSC initiated LCLS break as described in clause 7.2.1 and once the LCLS break is complete then begin applying the tone or announcement, or

– request temporary send access to the user plane as described in 14.6.2

If a node (subsequent CN node or BSS) does not support the procedures described for requesting temporary send access then a full LCLS break shall occur.