A call shall receive priority treatment (priority access to voice or traffic channels) on the originating side, when the call is setup by a Service User using the priority service dialling procedure described in section 4.9.

A call shall receive priority treatment (priority access to voice or traffic channels) on the terminating side, when the call is setup by a Service User using the priority service dialling procedure described in section 4.9.

The Priority Service user shall receive priority call treatment/progression through the mobile network(s). A priority call should be given higher priority over normal calls in the originating mobile network, to interconnected networks (including the PSTN) and in the terminating network. Note: The ISDN MLPP feature may be used for signalling of priority level in the core network.

Priority Service assumes a signalling channel is always available. When a Priority Service call encounters a "no radio available" condition in the call path involving an access or egress air-interface, or both, and,

• at call origination, and upon recognition of the Priority Service dialing pattern, the Priority Service call is queued in the cell serving the calling party and processed for the next available radio channel in that cell in accordance with the caller's priority level and call initiation time.
• at call termination upon recognition of a priority call indication in an incoming call, the Priority Service call is queued in the cell serving the called party and processed for the next available radio channel in that cell in accordance with the call's priority level and arrival time.

The Priority Service subscriber shall be assigned one of n priority levels. Priority levels are defined as 1, 2, 3,…,n , with 1 being the highest priority level and n being the lowest priority level. Refer to Annex A for Regional requirements for priority levels.

Priority Service is invoked only when requested and an idle voice or traffic channel required for an origination request is not available. If an idle voice or traffic channel is available when Priority Service is requested, the origination request is allowed to proceed normally without delay. Invocation of Priority Service at access (origination), during call progression (end-to-end), or egress (termination) is considered complete when one of the following occurs:

• A radio (voice or traffic) channel is assigned to the call (at origination or termination),
• The loss of radio contact or roaming to another PLMN provider's system (at origination only),
• The subscriber cancels the request by pressing the END key.
• Expiration of the maximum allowed time to hold for the next available radio (voice or traffic) channel (at origination or termination), or
• Deletion of the Priority Service request due to arrival of a higher priority request coupled with lack of queue capacity (at origination or termination).

Priority Service shall be applicable to voice and data telecommunications services that require a voice or traffic channel assignment.

A subscriber invoking Priority Service on call origination is authorized based on the caller's subscription. It should also be possible for an additional second level of authentication (e.g., by the use of PIN) to identify that the user is authorized to make a priority call. In this case, authorization of the subscriber may be realized by the usage of a PIN. The PIN solution is for further study and needs to be standardized. The user priority levels (1-n) and the associated PINs are assigned by the appropriate national authority and are fixed, i.e., a subscriber may not be allowed to change the PIN or the priority level. Note: There are some concerns related to security for "PIN Authorization".

Priority Service is manually requested by adding on the Priority Service service code (SC) to the origination request, as in:

Priority Service shall be able to be supported during roaming when the roaming network supports Priority Service.

Priority Service shall be able to be supported during handover.

The system should record the following Priority Service charging data record (CDR) information, in addition to non-Priority Service CDR information:

1. Priority Service invocation attempts.
2. Call legs (origination and/or termination) on which Priority Service was used to gain access to the radio channel.
3. Recording of appropriate Priority Service information (e.g., Priority Level, PIN usage indication). Note: The value of recording this information in CDRs is for further study.

Priority Service shall be able to support queuing of Priority Service calls for trunk resources. Trunk queuing provides the capability to place a Priority Service call that has experienced a congestion condition for trunk resources (e.g., no circuit available) into a queue associated with a trunk group until a trunk becomes available or until a maximum trunk queuing time has expired. Priority Trunk Queuing applies to ISDN User Part (ISUP) and Multi-Frequency (MF) trunks.

As a service provider option, it shall be possible to offer Priority Service and eMLPP within the same network, but not to the same user.