This standard provides network-to-customer installation (CI) interface requirements for the connection of a Public Safety Answering Point (PSAP) CI to a network providing access to an Enhanced 911 switching system. The interface uses loop reverse-battery signaling with a CI-provided battery source. The interface allows users of the Enhanced 911 system to communicate with the PSAP CI and allows the Enhanced 911 system to transmit the caller's emergency service identification (CESID) information to the PSAP CI. The requirements of this standard apply at the Network Interface (NI). The NI is the point of interconnection between the telecommunication network (the network) and the customer premises wiring and equipment (the CI). The requirements cover the electrical characteristics of the network and the CI and the interactions necessary for a PSAP CI to receive a call from an Enhanced 911 system@ and if necessary@ to transfer the call to a secondary PSAP. The voicegrade transmission performance of the network or the CI is not covered. The PSAP database interface is outside the scope of this standard. The loop reverse-battery signaling interface described in this standard is for incoming calls to the CI and employs a customer installation-provided battery source.1 It is significantly different from the interface described in ATIS-0600411.2001 (R2011)@ which describes an interface that uses loop reverse-battery signaling with a network-provided battery source. It is also different from the interface described in ATIS- 0600405.2002 (R2011)@ which describes a loop-reverse battery interface for Direct Inward Dialing (DID) service. Multiple carriers may be involved in providing the transmission and signaling paths between the PSAP CI and the Enhanced 911 switching system. The interface between the carrier and the Enhanced 911 switching system or intermediate carrier-to-carrier interfaces are not covered in this standard. The signals that the network presents at the NI are the normal telecommunications system voltages and currents. Alerting signals are normally not encountered at the NI. Voltages and currents due to maintenance activities@ and abnormal voltages and currents that are the result of the environment (e.g.@ induced voltages and currents or lightning) are not covered in this standard. Tariffs@ contracts@ or regulatory acts in various jurisdictions may contain additional or more stringent requirements than those in this standard. Purpose The purpose of this standard is to assist carriers@ end-users@ and manufacturers by providing network-to- CI interface requirements for analog voicegrade Enhanced 911 switched access to a PSAP CI using loop reverse-battery signaling with a CI-provided battery source. This standard is a living document subject to revision and updating as warranted by advances in network and equipment technology. 1 When Enhanced 911 PSAP access is implemented via DS1 using robbed-bit signaling@ the signaling states are the same as those transmitted by an interface historically known as Dial Pulse Terminating (DPT) that is described in ATIS-0600403.1999 (R2012).