Content for  TR 22.952  Word version:  18.0.1

As a Service Provider option, it should be possible to offer Priority Service and eMLPP within the same network, but not to the same user. See Annex B for Use Cases. Priority Service is a subscription-based service, based on eMLPP service. If eMLPP is provisioned in the network, the lowest eMLPP priority level (4) is the default for non-Priority Service users and does not involve any priority treatment. For priority treatment, a Service User receives treatment that is compliant with eMLPP service capabilities with the following exceptions, extensions, or clarifications:

• Support for an MS that is not eMLPP compatible is required.
• Support for the eMLPP Automatic Answering capability is not required.
• Support for Voice Broadcast Calls (VBS) and Voice Group Calls (VGCS) is not required.
• Priority Service applies to the Service Provider's entire permanent public GSM network.
• Support for Fast Call Set Up is not required.
• Support for Automatic invocation on call set up is not required.
• Service Users are able to invoke only their assigned priority level.

Priority Service call attempt overrides any eMLPP priority levels received from eMLPP capable mobile phones. That is Priority Service users are able to only invoke their assigned priority level, even if a Service User has indicated an eMLPP priority level when attempting a Priority Service call with an eMLPP capable phone. The TS 48.008 priority levels of Priority Service users are higher than the priority levels of any other eMLPP users. It should be noted that eMLPP also provides a priority level "A" that is intended for use internally by Service Provider technicians engaged in sustaining service availability. Priority level A is not intended for subscription and is not considered part of Priority Service. Such Service Provider technicians, when using eMLPP priority level "A", are viewed as part of Service Provider operations. There is no impact on the functionality offered neither to eMLPP subscribers in an eMLPP only network nor to Priority Service subscribers in a Priority Service only network.

Service Users are not allowed to invoke Priority Service calls through call forwarding or re-direction (e.g., "*SC + termination address" as a forwarded-to number, or Priority Service invocation through other re-direction services, such as IN DP12 Redirection etc.). If a Service User attempts to register "*SC + Destination Number" as a forwarded to number, the registration attempt fails. An incoming Priority Service call is forwarded to the Call Forwarding Unconditional (CFU) number if CFU is active. The calling Service User's priority level is passed during the forwarding process. An incoming Priority Service call is forwarded to the Call Forwarding Busy (CFB) number if CFB is active and if the called party's MS is busy. The calling Service User's priority level is passed during the forwarding process. An incoming Priority Service call is forwarded to the Call Forwarding No Reply (CFNRy) number if CFNRy is active and if the incoming call is not answered. The calling Service User's priority level is passed during the forwarding process. An incoming Priority Service call is forwarded to the Call Forwarding Not Reachable (CFNRc) number if CRNRc is active and if the called party's MS is not reachable. The calling Service User's priority level is passed during the forwarding process. If the called party has invoked Call Deflection (CD), an incoming Priority Service call is deflected to the deflected-to number. The calling Service User's priority level is passed during the deflection process. An incoming Priority Service call is forwarded to the Forward-to number if the call is forwarded by a CAMEL-based feature. The calling Service User's priority level is passed during the forwarding process.

Priority Service call users do not receive an incoming call indication while the call is being queued. Call Waiting applies only to active calls. No special interaction is applicable between Priority Service and Call Waiting; thus a Service User with an originating Priority Service call in queue is not informed of an incoming call while queued.

There is no interaction between Priority Service and emergency calls. If a service user dials *SC + [emergency call number], the call either receives radio traffic channel priority access treatment based on the service user's priority level or the call is denied. If a non-service user dials *SC + [emergency call number], the call is denied.

There is no interaction with ALS. This document assumes that Priority Service calls are made on the user's primary line, but they may also be made on the user's alternate line, subject to ALS restrictions, if the alternate line has the Priority Service subscription.

There is no interaction between Priority Service and asynchronous data calls.

It is recognized that Priority Service call processing may be modified by interactions with CAMEL and IN-based features.

Barring of Outgoing Calls (BAOC), Barring of outgoing International Calls (BOIC) and Barring of Outgoing International Calls except to Home PLMN Country (BOIC-exHC) are subscription-based features and take precedence over Priority Service.

There is no interaction between Priority Service and Call Transfer.

For MPTY calling, the manner in which the initial call is processed is based on how the call was initiated (e.g., as a normal call or a Priority Service call). If a Service User, after establishing an initial (either normal or Priority Service) call, initiates a MPTY call by dialling (*SC + Destination Number), the call is treated as a Priority Service call and is routed to the Destination Number. The calling Service User's priority level is passed during the process.

Priority Service applies only to post-paid calls. Users are not allowed to subscribe to Priority Service and Prepaid. If a Priority Service call is placed to a terminating Prepaid subscriber, the call may be released if the called party's account balance is insufficient to accept the incoming call, or the call may be dropped during the conversation if the balance is exhausted.

Priority Service is not applicable to SMS transmissions.

No interactions with other supplementary services described in TS 22.004 have been identified.

The call set-up signalling between networks must be such that it can guarantee correct handling in transit networks and in the terminating network. This means that the signalling has to be able to distinguish between Priority Service and eMLPP service offerings, by indicating the type of priority service and the priority level, as well as indicate whether pre-emption is allowed in transit nodes (if not implicitly indicated by the priority service type and priority level.) The only information that can be transferred between networks is as specified in the inter-network signalling systems. For this purpose, the 3GPP eMLPP specification states that interworking shall be done with the ISDN MLPP service. The signalling for the ISDN MLPP service, as specified in ISDN User Part (ISUP) and in Bearer Independent Call Control (BICC), is not designed to differentiate between these two types of priority services, i.e. between the Priority Service and eMLPP, and this seems not possible to solve with the current ISUP and BICC specifications as the parameters for the MLPP service are not sufficient to cope with both services. Examples of possible ways to solve this in ISUP and BICC would be to either expand the existing MLPP parameter to cope with both services, or to introduce a new parameter for the Priority Service, or reuse an existing parameter (e.g., ISUP Calling Party's Category, MLPP Service Domain). This work is outside the scope of 3GPP.

Support of Priority Service while roaming is primarily controlled through roaming agreements between Service Providers, but a Service Provider may also apply restrictions on the ability of incoming international roamers to invoke Priority Service. The Service Provider may configure the network such that Priority Service call invocation by international roamers is prevented (e.g., based on the Mobile Country Code (MCC) in the International Mobile Subscriber Identity (IMSI)). The Service Provider sends the Service User's eMLPP subscription information as applicable to Priority Service unaltered when sending subscriber data to the visited network with which there is a mutual business agreement covering Priority Service. The Service Provider is not required to send the Service User eMLPP subscription information to a visited network to which there is no mutual business agreement. Roaming is possible between an eMLPP only network and a Priority Service only network, i.e., between a) a network supporting eMLPP but not Priority Service and b) a network supporting Priority Service but not eMLPP. Service Users are not treated as being eMLPP subscribers when roaming into an eMLPP only network (i.e., treated like a non-eMLPP subscriber). eMLPP subscribers are not treated as being Service Users when roaming into a Priority Service only network (i.e., treated like a non-Priority Service subscriber). Roaming is intended to be backwards compatible with eMLPP specifications. See Annex B for applicable Use Cases.