This document fully specifies the P25 Tier 1 Location Service. Introduction The Project 25 Tier 1 Location Services specification describes how TIA-102 series standards and other industry standards are used to provide a location reporting service for P25 radio systems. This document was originally created by the TIA Project 25 Interface Committee (APIC) Data Task Group (DTG) for the purpose of describing the Location Services Architecture. It was edited in the TIA TR8.5 Data Sub-committee to transform it into a specification for P25 Tier 1 Location Services. P25 Location Services are divided into two tiers@ as described in the P25 Location Services Overview document. Tier 2 is defined in separate documents in the P25 Location Services document suite. This document specifies Tier 1 Location Services. Tier 1 supports a simple SU-to-SU interface for Conventional Direct or Repeated mode operation@ without providing IP addressing@ fixed host routing@ or more advanced configuration of triggering and reporting. This approach is appropriate for real-time field incident applications where the Location Service Host is resident on a portable device. It does not provide a mechanism to provide location information to a host device on a fixed network. The Tier 1 approach utilizes a dedicated Service Access Point on the P25 Common Air Interface to transport location information formatted as described in NMEA 0183@ a commonly used location protocol.