[ITU-T H.248.1] defines the international emergency preference scheme (IEPS) call indicator and priority indicator in support of priority services, e.g., the emergency telecommunications service (ETS) and the multimedia priority service (MPS). Use of the IEPS call indicator and priority indicator, as defined in [ITU-T H.248.1], satisfies the ETS requirements of indicating an ETS context and carrying the priority level.

Any prioritization of ITU-T H.248 procedures in the media gateway controller (MGC) and the transport of ITU-T H.248 control signalling towards the media gateway (MG) is based on the identification of ETS.

The IEPS call indicator, identifying an ETS call/session, indicates to the MG that the context is an ETS context and enables prioritization of ITU-T H.248 control signalling once received. In addition, it enables prioritized resource allocation in the MG for an ETS context.

The priority indicator, carrying the priority level, provides the MG with a means to distinguish different priority handling of resources on the MG when ETS is used.

This Recommendation provides guidelines on the use of the IEPS call indicator and priority indicator in ITU-T H.248 profiles for [ITU-T H.323] and NGN systems. These guidelines may be used by other standards development organizations (SDOs) when defining their ITU-T H.248.1 profiles in support of priority services (e.g., ETS and the MPS). Further details on how these guidelines are used by other networks are outside the scope of this Recommendation. It is up to other SDOs to decide their use when defining their profiles.

ETS and IEPS are defined in [ITU-T E.107] and [ITU-T E.106], respectively. ETS and IEPS involve authority-to-authority communication. The emergency indicator, as defined in [ITU-T H.248.1], is used for identification of emergency calls (i.e., individual-to-authority communication). The IEPS call indicator is used for the identification of a priority call/session (e.g., ETS call/session, IEPS call/session), allowing differentiation from an emergency call/session. The specification of profile procedures for the emergency indicator is outside the scope of this Recommendation.

National regulators may implement ETS in various ways. This Recommendation describes an implementation where the IEPS call indicator and priority indicator are supported.

NOTE 1 – National, regional or local emergency and public safety services, where an individual from the general public is seeking assistance (i.e., individual-to-authority communication), are outside the scope of this Recommendation.

NOTE 2 – [b-ITU-T Q-Sup.53] provides the signalling requirements to support the IEPS. It is also applicable for ITU-T H.248 entities, but does not indicate any requirement in addition to clause 7.

NOTE 3 – [b-ITU-T Q-Sup.57] provides the signalling requirements to support the ETS in IP networks. It is also applicable for ITU-T H.248 entities, but does not indicate any requirement in addition to clause 7.