The Vonage web site is decidedly user hostile so I was unable to get a usable
URL to the pertinent section.  I did find this under HELP - Features - Fax
Service:

>You can use your Vonage fax service while using the bandwidth saver mode. If you have enabled the
bandwidth saver option, simply enter "*99" prior to making a fax call (enter *99 plus the 11 digit
number). This will enhance the fax quality and prevent issues with your fax failing to go through.
>
>If you have one of the following products, it will automatically detect a fax or TiVo call, so it
is not necessary to dial *99:
>
>    * Linksys RTP300
>    * Linksys WRTP54G
>    * Uniden UIP1869V
>    * Motorola VT2442

Vonage also suggests setting your fax machine to a maximum baud (this is really
the wrong term but I am quoting them) rate of 9600.  I had an interesting email
discussion with a list member concerning fax compatibility with VOIP.  You may
want to do a Google search for "T.38" to learn more.

On Sat, 16 Sep 2006 17:37:07 -0700, you wrote:

>Ive just added a set of 150K pipes for Vonage to directly use, and have been
>checking on port forwarding (the 10000-20000 block is forwarded, and I've
>tried forwarding the other ports but with no change in quality).  However I
>still am getting some fairly poor voice quality and not able to complete the
>data transmissions.  If someone could find that dialing prefix that would be
>great.