日韩欧美亚洲 _ 欧美亚洲一区 _ 日本亚洲欧美 _ 亚洲精品欧美 国产白袜脚足J棉袜在线观看_亚洲熟妇av一区二区三区_久久天天躁狠狠躁夜_精品众筹模特私拍在线

單項(xiàng)選擇題

What is a benefit of Internet protocol (IP) telephony?()

A.Synchronizes password exchanges for call setup
B.Creates an encrypted tunnel for voice through a Transmission Control Protocol (TCP)/IP network
C.Enables two-way voice transmission over a packet-switched TCP/IP network
D.Eliminates the need for physical cabling in a TCP/IP network

微信掃碼免費(fèi)搜題