The disadvantage of Internet telephony is ( ).
A. Free to call.
B. Quality of call.
Connecting to all the place.
D. A, B and C.
查看答案
VoIP hardware and software work together to use the Internet to transmit telephone calls by sending voice data in packets using ( )
A. IP
B. traditional circuit transmissions.
C. IP and traditional circuit transmissions.
D. Radio
The incorrect choice about E-mail is ( ).
A. You can compose an e-mail message and send it to another person anywhere.
B. Some e-mail systems are confined to a single computer system or network.
C. It takes at least an hour for an e-mail to arrive at its destination.
D. E-mail is the transmission of messages over communications networks.
If you want to join Internet Relay Chat discussion ( ).
A. IRC client
B. Internet access
C. IRC host
D. A and B
If you want to join a video-conferencing, the hardware you may need are ( ).
A. Video camera, microphone and speakers.
B. Microphone, speakers and keyboard.
C. Mouse, microphone and speakers
D. Switch, mouse and keyboard
微信支付 
支付宝支付