ETSI ES 203 178 describes the unified functional architecture to support requirements as outlined in European Commission (EC) mandate M/493 [i.4] on emergency caller location determination and transport, in particular for the case where the VoIP service provider and one or several network operators - all serving the customer in the establishment of an emergency call - are independent enterprises needing to co-operate to determine the location of the (nomadic) caller. The architecture identifies all necessary interfaces, which are needed to fulfil the requirements outlined in EC Mandate M/493 [i.4], and provides a basis for the specification of the protocols to be used on those interfaces.

The present document is applicable to both NGN and pre-NGN IP-based networks. The architecture defined in the present document is intended to be compatible with IMS-based deployments but does not require compliance to IMS specifications.

This architecture does not intend to replace existing deployed solutions. It should enable operators and undertakings providing services to realize transmission of location information to the Public Safety Answering Point.