We are currently running AT&T CallVantage VoIP for our phone service
for two of the four lines we have in our house. This setup works fine
with our cable modem through its Ethernet port. We are now seeking to
switch over the two remaining lines as well to the CallVantage VoIP
service. This switchover requires the purchase of a second CallVantage
box (both are D-Link) because each box can only handle a maximum of
two phone lines. Therefore, our question is that our cable modem
supplied by Comcast (RCA DCM-325) has only one Ethernet port and a USB
port. In order for the second box to work, we need to send a signal
directly from the cable modem to the second CallVantage box (instead
of going through a router). We purchased a USB to Ethernet converter
but the cable modem cannot recognize this device and/or is not even
sending a signal to the device. It should be noted that we purchased a
second dynamic IP address from Comcast so that this approach should
work. As a result, we are attempting to either - 1) locate a
reasonably priced modem that has two Ethernet port outputs or 2) load
a driver to the DCM-325 that will allow it to recognize the USB to
Ethernet converter. By this we need to obtain the appropriate driver
and determine how to load it on the modem or 3) another solution
recommended by Comcast on how to connect a second modem without
purchasing a second account. As a side note, we purchased a second
modem and split the signal from the incoming cable before it reached
either modem. This worked fine but in order for the second modem to be
activated, we would be charged for a second account by Comcast,
thereby eliminating any cost savings by using the VoIP approach.

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Clarification of Question by sam123boo-ga on 08 Mar 2005 13:05 PST

I appreciate your speedy comment, Neutron, but as easy as it may seem
I cannot use a switch, hub or router. Due to AT&T's poor design, it
has to be DIRECTLY connected to the modem; litterally. Hence the need
for 2 modems. But your 2nd comment was interesting and very useful. I
wish I had known that before I bought the adapter.

1) Why can't you just use a router to distribute the internet
connection to both CallVantage boxes, like so?


cable modem->Router->Callvantage Box #1
                   ->Callvantage Box #2

Then there wouldn't be any need for second IP address/modems. I don't
see why it shouldn't work with a router in between.

2) You can't convert USB back to Ethernet. I have looked for such
adapters and haven't found any. Altough you can convert Ethernet to
USB. You seem to be having the same kind of problem as in this thread.
       http://answers.google.com/answers/threadview?id=470769

If you could you supply the brand & model number of the CallVantage
box, I will look into this.

Keep in mind that if you have a router set up correctly, your
CallVantage box should not know or care that there is a router in
between. I don't see why you can't use a router. Have you tried it?
What was the result?