FirewallFirewall is a network security system used for preventing unauthorized access to or from a private network.sessions for Lync or Skype for Business desktop-sharing and file-transfer are not allowed. Manually open a range ofTCPTransmission Control Protocol. TCP is a communication protocol that defines the standards for establishing and maintaining network connection for applications to exchange data.ports under the user role to allow Lync or Skype for Business desktop-sharing and file-transfer traffic. To allow a specific range of ports in the user role, refer the Microsoft Technet article which describes the port ranges used by Lync or Skype for Business clients and servers. Before media transmission, a Lync or Skype for Business client initiates a Session Traversal Utilities forNATNetwork Address Translation. NAT is a method of remapping one IP address space into another by modifying network address information in Internet Protocol (IP) datagram packet headers while they are in transit across a traffic routing device.(STUN) connectivity check. Sessions created by STUN are subjected to media classification that classifies the media as Real-time Transport Protocol (RTPReal-Time Transport Protocol. RTP is a network protocol used for delivering audio and video over IP networks.) or non-RTPReal-Time Transport Protocol. RTP is a network protocol used for delivering audio and video over IP networks.. ThefirewallFirewall is a network security system used for preventing unauthorized access to or from a private network.automatically allows theRTPReal-Time Transport Protocol. RTP is a network protocol used for delivering audio and video over IP networks.session on themanaged deviceand denies the non-RTPReal-Time Transport Protocol. RTP is a network protocol used for delivering audio and video over IP networks.sessions.

The STUN connectivity check is always enabled irrespective of whetherfirewallFirewall is a network security system used for preventing unauthorized access to or from a private network.visibility orDPI深度数据包检测。DPI is an advanced method of network packet filtering that is used for inspecting data packets exchanged between the devices and systems over a network. DPI functions at the Application layer of the Open Systems Interconnection (OSI) reference model and enables users to identify, categorize, track, reroute, or stop packets passing through a network.is disabled.