Business TeleCommunications (BTC) - Ordinary and Special quality voice bandwidth 4-wire analogue leased lines (A4O and A4S) - Terminal equipment interface; English version ETS 300453:1996
Access and Terminals (AT) - Ordinary and special quality voice bandwidth 4-wire analogue leased lines (A4O and A4S) - Terminal equipment interface (Endorsement of the English version EN 300453 V 1.2.1 (2001-07) as German Standard)— 1 стр.
