Yealink SIP-T19 E2 T4 Series, Administrator'S Manual

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Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series IP Phones
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To configure VPN via phone user interface after uploading a TAR file:
1.
Press
Menu
->
Advanced
(default password: admin) ->
Network
->
VPN
.
2.
Press or , or the
Switch
soft key to select the desired value from the
VPN Active
field.
You must upload the OpenVPN TAR file using configuration files or via web user interface
in advance.
3.
Press the
Save
soft key to accept the change.
A dialog box pops up to prompt that the settings will take effect after a reboot.
4.
Press
OK
to reboot the phone.
Network Address Translation (NAT)
Network Address Translation (NAT) is one of the technologies for solving the network problem –
the shortage of IP addresses. Many countries provide only one public IP address for complete
companies. They configure NAT to advertise the IP address for the entire network to the outside
world. This can reduce the need for a large number of public IP addresses.
NAT is essentially a translation table that maps public IP address and port combinations to
internal private ones. NAT ensures security since each outgoing or incoming request must first
go through a translation process.
NAT Types
Symmetrical NAT
In symmetrical NAT, the NAT router stores the address and port where the packet was sent. Only
packets coming from this address and port are forwarded back to the private address.
Full Cone NAT
In full cone NAT, all packets from a private address (for example, iAddr: port1) to public network
will be sent through a public address (for example, eAddr: port2). Packets coming from the
address of any server to eAddr: port2 will be forwarded back to the private address (for example,
iAddr: port1).