Integrated Services Digital Network (ISDN); circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for speech information transfer; service description; english version ETS 300109:1992
综合业务数字网(ISDN);可用于语音信息传输的电路模式64kbit/s 8kHz结构化承载业务类别;服务描述;英文版ETS 300109:1992