This use case is intended to illustrate that today's existing eMLPP networks are not disturbed by the new Priority Service + eMLPP functionality.
Use case 6:
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Two eMLPP subscribers each with assigned maximum and default priority (precedence) levels in the range of eMLPP1 - eMLPP7 belong to two different old networks (A and D) supporting eMLPP only.
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The eMLPP subscribers roam to two different new networks supporting both Priority Service and eMLPP (B and C) where they will have priority (precedence) levels in the range of eMLPP3 - eMLPP7.
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The eMLPP subscriber in (B) sets up an eMLPP call towards the eMLPP subscriber in (C).
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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. Priority Service calls should not be pre-empted by eMLPP calls.