
    <p>
      <em>
        Voice over Internet Protocol (VoIP), also known as IP telephony,
        is a set of technologies used primarily for voice communication
        sessions over Internet Protocol (IP) networks, such as the
        Internet. VoIP enables voice calls to be transmitted as data
        packets, facilitating various methods of voice communication.</em>
    </p>
    <ul>
      <li>
        Voice over IP - <a
          href="https://en.wikipedia.org/wiki/Voice_over_IP"
          rel="noopener noreferrer" target="_blank">
          https://en.wikipedia.org/wiki/Voice_over_IP</a>
      </li>
      <li>
        Plain Old Telephone System (POTS) - <a
          href="https://en.wikipedia.org/wiki/Plain_old_telephone_service"
          rel="noopener noreferrer" target="_blank">
          https://en.wikipedia.org/wiki/Plain_old_telephone_service</a>
      </li>
      <li>
        Retirement of circuit-switched public switched telephone network
        (in the UK) - <a
href="https://en.wikipedia.org/wiki/Telephony_copper_plant_retirement_in_the_United_Kingdom"
          rel="noopener noreferrer" target="_blank">
https://en.wikipedia.org/wiki/Telephony_copper_plant_retirement_in_the_United_Kingdom</a>
      </li>
      <li>
        Session Initiation Protocol (SIP) - <a
          href="https://www.ietf.org/rfc/rfc3261.txt" rel="noopener
          noreferrer" target="_blank">
          https://www.ietf.org/rfc/rfc3261.txt</a>
      </li>
      <li>
        Network Address Translator (NAT) - <a
          href="https://datatracker.ietf.org/doc/html/rfc2663"
          rel="noopener noreferrer" target="_blank">
          https://datatracker.ietf.org/doc/html/rfc2663</a>
      </li>
      <li>
        Session Traversal Utilities for NAT (STUN) - <a
          href="https://datatracker.ietf.org/doc/html/rfc5389"
          rel="noopener noreferrer" target="_blank">
          https://datatracker.ietf.org/doc/html/rfc5389</a>
      </li>
      <li>
        Voice over IP Companies - <a
          href="https://en.wikipedia.org/wiki/List_of_VoIP_companies"
          rel="noopener noreferrer" target="_blank">
          https://en.wikipedia.org/wiki/List_of_VoIP_companies</a>
      </li>
      <li>
        Voice over IP Hacking - <a
          href="https://en.wikipedia.org/wiki/VoIP_vulnerabilities"
          rel="noopener noreferrer" target="_blank">
          https://en.wikipedia.org/wiki/VoIP_vulnerabilities</a>
      </li>
    </ul>
    <p>
      <br>
    </p>
    <p>
      <br>
    </p>