Business TeleCommunications (BTC) - Ordinary quality voice bandwidth 4-wire analogue leased line (A4O) - Connection characteristics and network interface presentation; English version ETS 300451:1996
Access and Terminals (AT) - Ordinary quality voice bandwidth 4-wire analogue leased line (A4O) - Connection characteristics and network interface presentation (Endorsement of the English version EN 300451 V 1.2.1 (2001-07) as German Standard)— 1 стр.
