These settings shown below can guide you through many Cisco/Linksys ATA or Linksys routers.
The Cisco/Linksys RT41P2 and RT31P2 router VoIP ATAs have been in existence for several years now and have proven themselves as very stable devices. These VoIP routers are excellent for networks that want one device to act as both the LAN gateway device and ATA. Linksys designed these devices so the voice would be first in line for incoming traffic eliminating many of the problems that can occur when NAT (Network Address Translation) occurs before the VoIP ATA, causing routing problems. If you are connecting one of these VoIP routers to a DSL modem you will want to set it up to connect using PPPoE (Point to Point Protocol over Ethernet), authenticating on the RT41P2. This configuration would be the best for VoIP stability and should be done after bridging the DSL modem.
Note: The RT41P2 (and 31) routers are still available, but most users now get the Cisco SPA router ATAs.
The front of the RT41P2 ATA/router has a power light, 4 lights showing each of the 4 LAN Ethernet ports and 2 lights showing VoIP telephones Lines 1 and 2.
The rear of the RT41P2 VoIP router has an Internet port, 2 phone RJ11 phone connections, 4 RJ45 LAN ports, a reset button and a DC power connection.
To configure the Linksys RT41P2 (or most other versions of Cisco/Linksys VoIP routers, i.e. RT31P2) router would be to connect your computer's Ethernet cable directly to one of the Ethernet LAN ports in the Linksys Router/IAD and power up the VoIP Router and then power up your computer.
On the Setup page Click on the Internet Connection Type drop down box and choose PPPoE. Once PPPoE is selected, enter your PPPoE DSL username and password provided by your DSL Internet Service Provider into the appropriate fields. The DSL username format can vary from ISP to ISP so make sure to enter it exactly how your DSL provider suggests. If the Keep Alive option is not selected, be sure to select it instead of the "Connect on Demand" option. The Keep Alive option will ensure your Internet connection is connected even when it is not in use, which is very important so you will receive phone calls.
Next scroll down to the bottom of the Setup page and select Save Settings or Apply to save your changes. At this point you may be prompted that a reboot will be required. Click OK if needed, if not then navigate to the Status page.
If on the Status page you see Connected, your connection should good. If however, your connection show not connected, press the Connect Button to authenticate with your ISP.