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

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

A.
Synchronizes password exchanges for call setup

B.
Eliminates the need for physical cabling in a TCP/IP network

C.
Enables two-way voice transmission over a packet-switched TCP/IP network

D.
Creates an encrypted tunnel for voice through a Transmission Control Protocol (TCP)/IP network