ETSI ETS 300 049-1992 综合业务数字网(ISDN).ISDN分组模式承载业务(PMBS).由用户接入的D信道提供的ISDN虚拟呼叫(VC)和永久虚电路(PVC)承载业务.基本速率和基群速率
Integrated Services Digital Network (ISDN); ISDN Packet Mode Bearer Service (PMBS) ISDN Virtual Call (VC) and Permanent Virtual Call (PVC) Bearer Services Provided by the D-Channel of the User Access - Basic and Primary Rate