5 Normal operation with successful outcome

3GPP42.068Release 17Stage 1TSVoice Group Call Service (VGCS)

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.1 Provision

The VGCS is provided to be used by the service subscriber after prior arrangements with the service provider. The provision includes the assignment of group Ids to the service subscriber. A subscription shall not provide more than 50 group Ids to the service subscriber.

The service can be offered with one subscription option:

Subscription option	Value
– subscriber has the capability of initiating voice group calls in case of roaming	– No
	– Yes.

5.2 Withdrawal

The VGCS is withdrawn at the service provider’s request or for administrative reasons.

5.3 Network related service configuration

The network related service configuration defines the attributes of a particular voice group call which shall be pre-registered in the network by the service provider. This is not related to one specific service subscriber.

The attributes of a particular voice group call are group ID, group call area composition, a list of dispatcher identities to be connected to this area, a list of dispatchers allowed to initiate voice group calls to this area, the group call reference which shall be used in case of COLP (see subclause 7.3) and recipient identities to which an optional acknowledgement can be routed. Changes to the group call area composition shall be co-ordinated with the network operator.

5.3.1 Void

5.4 Normal operation for voice group call establishment

The VGCS shall be automatically initiated by the network when a calling service subscriber or calling dispatcher dials a particular short code or address at call set-up.

On successful initiation of the VGCS, the voice group call shall be established between the calling service subscriber or calling dispatcher and the destination subscribers. The destination subscribers are:

– all destination service subscribers at any time during the voice group call with the corresponding active group ID when located in the group call area where the group call area is uniquely defined by:

– the location (radio cell) of the calling service subscriber at invocation if the call is originated by a calling service subscriber;

– the addressed group call area if the call is originated by a calling dispatcher;

– the pre-registered destination dispatchers related to that group call area and group ID.

The calling service subscriber or calling dispatcher shall be informed by the network with a suitable indication about the successful establishment of the voice group call so that the user can start to speak.

The call can be released by the calling service subscriber or by the calling dispatcher or by the network or by an entitled dispatcher predefined in the network.

Destination subscribers may exit the voice group call separately without releasing the complete voice group call.

5.5 Charging requirements

Event data may be recorded as a network option as defined in 3G TS 32.005 for all VGCS calls to one group ID in a specific group call area. In addition other data to be passed to the anchor MSC for charging purposes are the identities of the talking subscribers, the time in which they were active and the resources (i.e. cell identities) used during a call.

5.6 Security requirements

VGCS shall be able to support over-the-air ciphering in order to provide confidentiality protection to group calls.

VGCS ciphering is an operator’s option.

VGCS shall provide means such that only a legitimate service subscriber is able to participate in a ciphered VGCS call when the operator requires confidentiality protection for the group call. To include a subscriber into a ciphered voice group the required group data shall be stored on the USIM. Storing these group data on the USIM may be done e.g. during the USIM personalisation process or via OTA (over-the-air) provisioning.

– If the operator configures confidentiality protection for p-t-p SMS over the CS domain then, it shall also apply when a p-t-p SMS is sent/ received by VGCS group call members in parallel to the voice group call.

– If the operator configures confidentiality protection for the group call then, confidentiality protection at least equivalent to that provided for the ongoing group call shall apply when a group call member sends a SMS to the group call.

– If the operator configures confidentiality protection for p-t-p SMS over the CS domain then, it shall also apply to a SMS which is sent by a group call member to a different group, in parallel to the voice group call.

A pre- Rel-6 VGCS capable mobile shall be able to participate in an un-ciphered group call, if it is part of that group.

An operator shall be able to guarantee privacy for a SMS sent by a group call member to a different group. This ensures that the SMS cannot be intercepted by members of the sender’s group.