Yealink SIP-T54S Administrator's Manual page 123

Press the Save soft key to accept the change.
5.
A dialog box pops up to prompt that the settings will take effect after a reboot.
Click OK to reboot the phone.
6.
VPN
VPN (Virtual Private Network) is a secured private network connection built on top of public
telecommunication infrastructure, such as the Internet. It has become more prevalent due to
benefits of scalability, reliability, convenience and security. VPN provides remote offices or
individual users with secure access to their organization's network.
VPN Technology
IP phones support SSL VPN, which provides remote-access VPN capabilities through SSL.
OpenVPN is a full featured SSL VPN software solution that creates secure connections in
remote access facilities, designed to work with the TUN/TAP virtual network interface. TUN and
TAP are virtual network kernel devices. TAP simulates a link layer device and provides a virtual
point-to-point connection, while TUN simulates a network layer device and provides a virtual
network segment.
IP phones use OpenVPN to achieve VPN feature. To prevent disclosure of private information,
tunnel endpoints must authenticate each other before secure VPN tunnel is established. After
VPN feature is configured properly on the IP phone, the IP phone acts as a VPN client and uses
the certificates to authenticate the VPN server.
To use VPN, the compressed package of VPN-related files should be uploaded to the IP phone
in advance. The file format of the compressed package must be *.tar. The related VPN files are:
certificates (ca.crt and client.crt), key (client.key) and the configuration file (vpn.cnf) of the VPN
client.
The following table lists the unified directories of the OpenVPN certificates and key in the
Setting Up Your System
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