Which of the following protocols is not directly related to VOIP?

Which of the following protocols is not directly related to VOIP?

• Real-time Transport Protocol (RTP)
• Session Initiation Protocol (SIP)
• File Transfer Protocol (FTP)
• Inter-Asterisk eXchange (IAX) 

 

EXPLANATION

Voice over Internet Protocol (also voice over IP, VoIP or IP telephony) is a methodology and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet.
Voice over IP has been implemented in various ways using both proprietary protocols and protocols based on open standards. VoIP protocols include:

Session Initiation Protocol (SIP) H.323Media Gateway Control Protocol (MGCP) Gateway Control Protocol (Megaco, H.248) Real-time Transport Protocol (RTP) Real-time Transport Control Protocol (RTCP) Secure Real-time Transport Protocol (SRTP) Session Description Protocol (SDP) Inter-Asterisk eXchange (IAX) Jingle XMPP VoIP extensions Skype protocol

SOURCE

https://en.wikipedia.org/wiki/Voice_over_IP