ETSI ES 200 778-4 English Printed Edition English PDF Final draft Version 1.1.1Access and Terminals (AT); Analogue access to the Public Switched Telephone Network (PSTN); Protocol over the local loop for display and related services; Terminal equipment requirements; Part 4: Test Suite Structure and Test Purposes (TSS &TP); On-Hook and Off-Hook

standard published 02/01/2002 by European Telecommunications Standards Institute