The Mobile Station may indicate the priority of each call initiated. If no priority is indicated by the user or a non-compatible Mobile Station is used then the default priority level shall be applied which is stored in the VLR. The selection of priority shall be an MMI function. Mobile stations indicate the priority of their call in the signalling that takes place during the call establishment process. No preferential treatment will be possible during this initial random access until the point at which the priority information is received by the network (CM_SERV_REQ message). Alternatively, a resource pre-emption might already take place on basis of an establishment cause. In GSM, prior to the indication of the selected priority level in the CM_SERV_REQ message, the BSC may decide on the assignment of an SDCCH or direct assignment of a TCH on the basis of the establishment cause in the CHAN_REQ message. This allows the BSC to support a fast call set-up at the earliest stage of the call establishment. The establishment cause for emergency calls or an establishment cause indicating the request for fast call set-up shall be able to trigger this function. In UMTS, prior to the indication of the selected priority level in the CM_SERV_REQ message, the RNC shall receive the establishment cause in the RRC CONNECTION SETUP REQUEST.

The Mobile Station shall verify the selected priority level against the priority levels stored in the SIM. If the selected priority is not allowed, then the priority of the call shall be modified to that of the nearest allowed priority level below the requested level. The MSC shall request the VLR to verify if the subscriber is allowed to use the selected priority level.

A GSM network may wish to omit or postpone authentication and ciphering in order to provide for a faster call set-up. If the network decides to omit or postpone authentication and ciphering for a call it can send a CM_SERV_ACC message in reply to the CM_SERV_REQ message.

In GSM, the channel assignment request to the BSC shall also include the priority level and pre-emption capability of the connection as defined in TS 48.008. The MSC maps the eMLPP priority on these priority levels. In addition, the eMLPP priority shall be explicitly indicated to the BSC in the assignment request. The BSC shall store the priority level in order to decide on later actions, e.g. to arrange notifications to the Mobile Station according to priorities. In UMTS, the RAB assignment request to the RNC may also include the priority level and pre-emption capability of the connection as defined in TS 25.413. The MSC maps the eMLPP priority on these priority levels. In addition, the eMLPP priority shall be explicitly indicated to the RNC in the RAB assignment request. Values for radio access bearer service attributes defined in TS 23.107 should be taken into account for mapping from eMLPP priority into priority related information element in RANAP. The RNC shall store the priority level in order to decide on later actions, e.g. to arrange notifications to the Mobile Station according to priorities.

If an appropriate radio channel is available the BSC (for GSM) or the RNC (for UMTS) shall assign it as normal. If no channels are available then the BSC (for GSM) or the RNC (for UMTS) shall perform queuing according to the priority levels. If the assignment request has a pre-emption capability indicator, pre-emption shall be performed. In addition, the network related service configuration defines the set-up class in relation to a priority level and therefore the allowable delay of the call establishment (see TS 22.067). By using this information, the MSC shall decide whether OACSU may be applied for a call or not.

The network shall include the assigned priority level in a CALL_PROCEEDING message if the network supports priority. The Mobile Station shall store the priority level requested by the user, possibly overridden by the level received by the network, to perform automatic answering of calls or pre-emption of on-going calls.

For a mobile terminated call, the priority level is defined in the ISUP set-up message to the VMSC. It may also be present in the MAP_PROVIDE_ROAMING_NUMBER request (see TS 29.002). The priority and pre-emption indications used in the ISUP shall follow the definitions of the MLPP service as defined in the ITU-T recommendations Q.85 and Q.735, respectively. In GSM, a PAGING REQUEST message on CCCH may also include a priority level as described in GSM 04.08 [10], clause 'Paging initiation using paging subchannel on CCCH'. In UMTS, if the MSC identifies a mobile terminated call as a high priority call based on local configuration of the eMLPP service, the MSC shall include in the Paging message the Paging Cause IE set to the value "Terminating High Priority Signalling".

In GSM, the channel assignment request to the BSC may include the priority level and pre-emption capability of the connection as defined in TS 48.008. The MSC maps the eMLPP priority on these priority levels. In addition, the eMLPP priority shall be explicitly indicated to the BSC in the assignment request. The BSC shall store the priority level in order to decide on later actions, e.g. to arrange notifications to the Mobile Station according to priorities. In UMTS, the RAB assignment request to the RNC may include the priority level and pre-emption capability of the connection as defined in TS 25.413. The MSC maps the eMLPP priority on these priority levels. In addition, the eMLPP priority shall be explicitly indicated to the RNC in the RAB assignment request. Values for radio access bearer service attributes defined in TS 23.107 should be taken into account for mapping from eMLPP priority into priority related information element in RANAP. The RNC shall store the priority level in order to decide on later actions, e.g. to arrange notifications to the Mobile Station according to priorities.

The network may wish to omit or postpone authentication and ciphering in order to provide for a faster call set-up according to the priority level to be applied for the call and the network specific service configuration stored in the MSC. If the network decides to omit or postpone authentication and ciphering for a call it, can send the SETUP message immediately after reception of the initial layer 3 message.

In this case the Mobile Station shall be paged in the normal manner, but with the paging messages also containing the priority level of the call. In addition, the priority level will be provided with the SETUP message. The Mobile Station in group receive mode shall consult the internal service configuration list stored on the SIM to check whether it should automatically respond to the paging request. If it does respond to the paging request and if a following Call Control SETUP message (received as a response to paging response) specifies a priority different from the one specified in the paging request, this fact is not a reason for the mobile station to reject the (point-to-point) call for which the SETUP message was received. The Mobile Station in idle mode does not need to analyse the priority level from the paging request message but can derive it from the SETUP message and then decide on automatic acceptance of the call. In the case where the called subscriber is using a non compatible Mobile Station, automatic answering is not possible.

In the case where the called subscriber has a subscription for eMLPP and for Call Waiting and is using a compatible Mobile Station, the Mobile Station shall be informed of the priority of the new call together with the call waiting indication. The Mobile Station will then consult the internal service configuration list stored on the SIM to establish whether it should automatically accept the waiting call without consulting the user, or whether the call waiting facility will be used as normal. In the case where the called subscriber has no subscription for Call Waiting, called party pre-emption is not possible. In the case where the called subscriber is using a non compatible Mobile Station and has a subscription for Call Waiting, Call Waiting shall be performed as normal.

For each voice group call or voice broadcast call service configuration registered in the GCR as defined in TS 43.068 and TS 43.069, respectively, a priority level is assigned at registration of the GCR data by the service provider. The priority level will be provided by the GCR together with the call attributes.

Authentication of the calling service subscriber shall be performed equivalent to the standard mobile originated call case as defined in clause 11.3.1.3. If the GCR response provides a priority level then the calling service subscriber shall be treated with the GCR defined priority. If not, then the calling service subscriber shall be treated with his selected priority or with his default priority as known in the VLR as long as he has an own link with the network (see TS 43.068 and TS 43.069). The priority which applies to the voice group call channel or voice broadcast call channel is defined in the GCR. Authentication and ciphering of the calling service subscriber might therefore be performed, omitted or postponed (see clause 11.3.1.3).

The priority level shall be indicated together with the related paging messages or notification messages and treated in the Mobile Station as defined in TS 43.068 and TS 43.069, respectively.