scope:

This standard provides specifications for E&M signaling interfaces between telecommunication carrier networks and customer installations. In this standard, the telecommunication carrier network is referred to as the Network and the customer premises wiring and equipment as the Customer Installation (CI). The interface between the Network and the CI will be known as the Network Interface (NI). The NI is the same as the demarcation point defined in Part 68 of the FCC Rules and Regulations (see Annex A).

This standard covers interfaces between Network and CI equipment units located in the same building that employ dc signaling methods known collectively as E&M signaling. E&M signaling methods use different leads for dc signaling and analog voicegrade signal transmission. Four methods of E&M signaling are covered:

- Type I - CI Originates on the M Lead;

- Type I - CI Originates on the E Lead;

- Type II - CI Originates on the M Lead;

- Type II - CI Originates on the E Lead.

These E&M signaling methods are illustrated in Figures 1 through 4.

E&M signaling interfaces are typically used with services, such as private network trunks (e.g., PBX tie trunks), that provide dedicated transmission and signaling paths between two CIs or between a network switching node and a CI. Many different signaling protocols may be used with E&M signaling. Signaling protocols are not covered by this standard, but are covered in other documents. For example, signaling protocols for PBX tie trunks are covered in ANSI/TIA/EIA-464-B, Requirements for private branch exchange (PBX) switching equipment.

Intermediate carrier-to-carrier-network interfaces that use E&M signaling are not addressed in this standard; however, this standard may be referenced for those interfaces when applicable. In such cases, the CI specifications would apply to one carrier network, the network specifications would apply to the other carrier network, and physical connection would be made in a manner mutually agreed upon by the carriers.

This standard also does not cover the voicegrade transmission performance of the network or the CI.

The voltages and currents described in this standard are those encountered during the normal operation of the interface. Abnormal voltages and currents caused by the network environment or the CI environment are not covered.