多项选择题
A.双流输出 B.内置MCU C.主叫呼集 D.实现NAT穿越
A.KDM2404LS B.KDM2401 C.KDM2500 D.KDM2501
A.KDM2404LS B.KDM2401 C.KDM2400 D.KDM2402