UNE-TBR 1:1999

TERMINAL EQUIPMENT (TE). ATTACHMENT REQUIREMENTS FOR TERMINAL EQUIPMENT TO BE CONNECTED TO CIRCUIT SWITCHED DATA NETWORKS AND LEASED CIRCUITS USING A CCITT RECOMMENDATION X.21 INTERFACE, OR AT AN INTERFACE PHYSICALLY, FUNCTIONALLY AND ELECTRICALLY COMPATIBLE WITH CCITT RECOMMENDATION X.21 BUT OPERATING AT ANY DATA SIGNALLING RATE UP TO, AND INCLUDING, 1 984 KBIT/S.