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By WelshPaul
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By default, the SPA122 VoIP ATA is configured to function as a NAT-Router and DHCP server. This allows the SPA122 to act as a suitable Internet gateway device for your local home or small office network.
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However, there may be times when you don't need or want to use the SPA122 in NAT DHCP server mode. For example, if you will be using the SPA122 behind an existing NAT-Router, you will likely be better off disabling the NAT functionality within the SPA122 ATA. In which case, you will change its Network Service Mode from NAT to Bridge.
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Here is How To Switch To Bridge Mode
  1. Login to the SPA122
  2. Click on Network Setup menu tab (top of window)
  3. Click on Network Service menu tab (left-side navigation window pane)
  4. In the Network Service window, click the Network Service drop-down option (default is NAT)
  5. Select the Bridge option.
  6. Click the Submit button.
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Once you click on Submit button, you will be greeted with a Warning pop-up dialogue. This is to let you know that the SPA122 and any other devices connected to its yellow Ethernet port will lose Internet and network connections for a few minutes while it reboots. Proceed by clicking on OK.
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Once you have clicked OK, the "Setting Saved Successfully" window pops up next.
This window will remain until the SPA122 completely reboots itself.

Actually, once rebooted you will likely need to enter a new IP address into the web browser. This will now be the IP address assigned to the SPA122 by your NAT-Router acting as the DHCP server on your LAN network. (You may need to use the phone port IVR to discover this new IP address: **** 110# in order to log back in.)
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Once the SPA122 has restarted, it will now be in Bridge Mode.

From here on, the SPA122 functions basically the same as if it was a SPA112 ATA. And, login will also be the same as if you were using the SPA112. What this means is that the SPA122 is now functioning as a standalone ATA without the built-in NAT-Router, Firewall, DHCP server, or QOS functionality. Just as if it were a SPA112. The only difference now is that the SPA122 has the extra yellow switch port that the SPA112 doesn't have. Any device connected to this yellow Ethernet port will also have the same connectivity available to it as any other devices connected to your LAN Router switch (as long as they are all on the same sub-net).

The IP address used to sign into the SPA122, while in bridge mode, will now be that as assigned to it by your network LAN DHCP server. (Remember when not in bridge mode, the SPA122 was accessible via the yellow Ethernet LAN port using its default gateway address of In bridge mode, that address will no longer be its default address.

And, while the SPA122 is in Bridge mode, its blue Internet Ethernet port needs to be connected to your existing network NAT-Router LAN port, or to a switch port that is also connected to your network NAT-Router LAN (and on the same sub-net). The blue Ethernet port will be acting as the Uplink port for the SPA122 two-port switch. You can now login to the SPA122 via any PC connected via the blue Internet Uplink port side (via the LAN Router or switch). Or, you can also login via a PC connected via the yellow Ethernet port - it's your choice.

Really, that's it for Bridge Mode. Now, you can think of the SPA122 as essentially the same as its sister ATA, the SPA112. Function and configuration is essentially identical between the two ATA's when the SPA122 is in Bridge Mode.
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By PY Bouvy
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Some complementary information from the practice:
When you switch from NAT to Bridge, the SPA 122 gets another IP from another router of your network. To find it, call ****110#. You know now which IP you have to connect to get access to the web page of the SPA 122 again.
If you want to have a fixed IP, you have to follow the procedure above and then go to Network setup, internet settings. Give a fixed IP address on this WAN section but an address from your own LAN-network. In bridge configuration, all becomes LAN and what WAN was, is now to be considered as LAN.
WelshPaul liked this

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