The purpose of this standard is to provide test equipment requirements and methods for testing the transmission characteristics of PCM telecommunications equipment, circuits, and systems. The test equipment requirements are intended to be suitable for certification, installation, pre-service, and out-of-service operational and in-service operational tests of the PCM transmission facilities. The PCM equipment that may be tested includes primary multiplex equipment containing A-D (Analog-Digital) conversion devices, digital multiplex equipment, digital links, and digital sections. This document is currently limited to testing at the analog interfaces of the primary multiplex equipment and the digital interfaces at DS1, DS1C, DS2, and DS3 levels of the North American digital hierarchy. Synchronous multiplex equipment and equipment offering other than 64 kb/s coded voiceband channels (e.g., 32 kb/s voiceband coding, 256 kb/s program, or 64 kb/s data) are not covered in this standard. Signaling parameter measurement is outside the scope of this document.