
Explanation:

Transport Control Protocol(TCP), User Datagram Protocol (UDP) ports, and Protocol Numbers are important to TCP/IP networking, intranets, and the Internet. Ports and protocol numbers provide access to a host computer. However, they also create a security hazard by allowing uninvited access. Therefore, knowing which port to allow or disable increases a network's security. If the wrong ports or protocol numbers are disabled on a firewall, router, or proxy server as a security measure, essential services might become unavailable.
TCP port 25 is used for simple mail transfer protocol which is used to e-mail routing between mail servers.
TCP port 443 is used for Audio, video and application sharing sessions as well as data sharing sessions.
RTP/UDP port 50020-50039 must be used for outbound video sessions.
RTP/UDP port 50000-50019must be used for outbound audio sessions.