Which protocol is primarily used by the IPO for voice communication?

The correct choice is the protocol primarily used by the IPO for voice communication, which is VoIP (Voice over Internet Protocol). VoIP technology enables the transmission of voice communications over the internet or other IP-based networks. It compresses voice signals into data packets, allowing for efficient and scalable voice communication solutions.

In the context of the IPO platform, VoIP is essential because it supports various features like call forwarding, voicemail, and conferencing—all integral to modern communication systems. VoIP also offers flexibility and cost savings compared to traditional telephone systems, making it a preferred choice for businesses.

Other protocols listed, such as HTTP, FTP, and SMTP, serve different purposes. HTTP is primarily used for transferring web pages, FTP is used for file transfers, and SMTP is used for sending emails. These protocols do not cater to voice communication, highlighting why VoIP is the most suitable and relevant choice for this question.