8 Interaction with other network features and services

22.1353GPPMulticallRelease 17Service descriptionStage 1TS


No impact.

8.2 IST

No impact.

8.3 ODB

No impact.

8.4 Emergency Calls

The network shall handle emergency call at first priority. When a user originates an emergency call, the network shall behave as follows:

  • The network, which supports Multicall, shall accept the emergency call within the serving network capability regardless of Multicall subscription limitation to the user.
  • The MS shall ensure that an emergency call setup request is acceptable to a serving network which does not support multicall, if necessary by releasing one or more existing call.

Annex A (normative):
Busy definition

NDUB (Network Determined User Busy) occurs when:

  1. The maximum number of mobile terminating calls (Ncs_MT) has been reached (NOTE 1).
  2. The maximum number of bearers (Nbr) has been reached and the maximum number of waiting calls has been reached (NOTE 2, NOTE3).

NOTE 1: This can occur even if bearers are still available, e.g. when the MS is engaged in MPTY SS. If the maximum number of mobile terminating calls (Ncs_MT) has been reached, the Call Waiting SS cannot be invoked.

NOTE 2: If Call Waiting is provisioned and activated, and when the maximum number of bearers has been reached the Call Waiting SS can be invoked. This case is not regarded as NDUB. See subclause 7.3.2 for interaction with Call Waiting SS.

NOTE 3: According to the speech bearer number limitation, the incoming speech call shall be regarded as encountering NDUB when the MS is engaged in a speech call (including a held call) and Call Waiting SS is not provisioned and activated for the user, irrespective of the further availability of bearers for the user. For the condition under which Call Waiting SS shall be invoked in this case, see subclause 7.3.2.

For User Determined User Busy (UDUB) condition see TS 22.001 Annex C.

Annex B (informative):
Cross Phase Compatibility

This section details the cross phase compatibility requirements relating to the service requirements in this document.

NOTE: When a change is introduced which affects the 3GPP specifications, it is said to be ‘backward compatible’ if existing equipment can continue to operate and perform correctly with equipment that conforms to the new implementation.