This use case is intended to illustrate the new Priority Service + eMLPP functionality fulfils the eMLPP requirements.
Use case 2:
Two eMLPP subscribers, each with assigned maximum and default priority (precedence) levels in the range of eMLPP1 - eMLPP7 belong to two different new networks (A and D) supporting both Priority Service and eMLPP or eMLPP only.
The eMLPP subscribers roam to two different new networks (B and C) supporting both Priority Service and eMLPP where they will have priority (precedence) levels in the range of eMLPP3 - eMLPP7.
The eMLPP subscriber in (B) sets up an eMLPP priority call towards the eMLPP subscriber in (C.)
The call is routed via an intermediate non-3GPP network.
In this use case, the call terminating in (C) is treated as a terminating eMLPP call with the priority level either as requested by the calling subscriber at the call set-up in (B) or, if not requested at call set-up, according to the default priority level assigned to the calling eMLPP subscriber. Since eMLPP Service is based on the eMLPP subscription of the calling party, this use case also applies to a called party without eMLPP subscription.
Priority Service calls should not be pre-empted by eMLPP calls.