What features does SIP support in addition to voice calls?

SIP, or Session Initiation Protocol, is a signaling protocol widely used for initiating, maintaining, and terminating real-time sessions that involve video, voice, messaging, and other communications. The correct answer reflects the comprehensive capabilities of SIP beyond just handling voice calls.

SIP supports a variety of communication types, including video conferencing, which allows multiple participants to engage in visual communication simultaneously. Additionally, it facilitates instant messaging, enabling users to send text-based messages in real time, which is essential for modern communication needs. Presence information is another crucial feature, allowing users to see the availability status of their contacts, enhancing the user experience in communication.

The other options do not encompass the full range of capabilities offered by SIP. While video calls are indeed a part of SIP's offerings, limiting its functionalities to only video does not represent the full spectrum of services SIP can provide. Similarly, focusing solely on fax services and traditional telephony overlooks the advanced multimedia capabilities that SIP supports. Lastly, data transfer and email services are not directly supported by SIP in the same way, as it is primarily focused on real-time communication rather than file-based communication or email handling. The correct answer accurately captures the versatility of SIP as it pertains to various modes of communication, reinforcing its role