Voice Over IP (VOIP) is the option that allows the transmission of voice and often video communication over the Internet. So, this doesn't refer to mobile or other telephone communication, but rather to the Internet solely. Applications that are examples of this type of technology are Skype, Teamspeak, Ventrilo, and others. This technology is becoming better and better with each day and will probably replace phones completely in the future.
If it is guranteed the key is only known to Alice and Bob and there is no risk of man in the middle attack or channel spoofing so we can achieve data origin authentication
