The vonage site has a help section for the cisco 186
http://vonage.com/help.php?category=40&nav=4
You will be able to find what ports to open.

http://vonage.com/help.php?article=152&category=40&nav=4


> > The linksys is simply a router with 1 wan port and 4 lan ports. The
> > Vonage unit is a Cisco 186 device (1 lan port, 1 phone port). This
> > unit is currently attached to one of the lan port of the linksys
> > router.

> > Cable modem -> m0n0 -> switch -> Cisco 186 -> phone line

Vonage http://vonage.com/help.php?article=88&category=40&nav=4
Vonage Note: This configuration does not allow the Phone Adapter to
prioritize your voice traffic.  The Quality of Service option requires
the phone adapter to be connected in front of your router.

> > I want to use m0n0 to give a higher priority to the VoIP packets.
> > Someone has suggested to research the VoIP threads on m0n0 and I'll
> > do that.
> >

M0n0wall does traffic shaping. Look into this if you have issues with
call quality