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Rich Tehrani


[June 28, 2004]


AT&T CallVantage: Checking Under the Hood




We reviewers would probably have nothing to write about if we actually read product manuals. Then again, who reads manuals anymore? Come to think of it, most products I receive these days don’t even have manuals. Well, I guess they do if you count a PDF file as a manual. Here is another episode in my exciting adventure of getting the latest technology to work properly.


I first installed the appropriate CallVantage (news - alert) equipment that was sent to me a few months back when AT&T (news - alert) first released the service. I wanted to write about it quickly so I decided to install it in my office the same day I received the package. Well, my office has a few T1s and trying to install the D-Link DVG-1120M telephony adapter (TA) behind my firewall was unsuccessful. So I connected to a fixed IP address which meant I had to turn off DHCP (define - news - alert) on the TA and configure the IP address, subnet, DNS servers, etc.


A few weeks ago I brought the TA home. I directly connected the TA into my cable modem and then connected my Linksys (news - alert) wireless router into the D-Link TA. This didn’t work, as I forgot that I turned DHCP off on the TA. I then installed the TA behind the Linksys device. This resulted in no phone service and no Internet. I gave up as it was late. I had to sleep and subsequently, go on a trip the next day.


Yesterday I replaced my Linksys router with a new Linksys 802.11g device the WT54G (it works great) and decided to figure out what was wrong with the TA. (define - news - alert) I turned on DHCP under the “WAN IP Address” section. Still, no luck. Nothing worked. I then decided that there was a DHCP conflict of some kind so I turned off the DHCP server on the TA. Still, no luck. I then decided that somehow the NAT setting was causing problem so turned off NAT (define - news - alert) on the TA. Still, no luck… nothing worked.


At this point I decided to take a break and have brainpower food (Planter premium Mixed Nuts – Atkins Friendly). I reemerged refueled and ready to tackle this thorny problem. I plugged the TA directly into the cable modem and voila, I had phone service! What a relief!


I went upstairs to get back to work and guess what? My computer didn’t work. I had noticed that D-Link was using the address while Linksys was using I changed the local IP address on the Linksys to and magically, I had internet access.


Once everything was running, I did some research and discovered others had problems getting the D-Link 1120M running behind a firewall. AT&T representatives had told me in the past that voice quality was paramount and obviously being in front of all other devices they can assure that they receive as much bandwidth as needed to ensure voice quality. I hope this article helps save you time, effort and energy when you install CallVantage for yourself. Of course, you could have just read the manual.


Rich Tehrani is TMC's president. He welcomes your comments. Participate in our forums.


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