samba - Mar 2001 - Can ping computers in another network, but can't see samba

Hi.  We have a successful samba server up and running on our local network.  
We also have a connection via a 3Com ATM router to another network.  I can 
ping computers on that network, and they can ping the samba server.  In 
network neighborhood I can see their computers.  They also see our 
Win9x/NT/2K systems under their network neighborhood, but they don't see the
samba server.  If I try to connect directly to a share using UNC 
(\\discfarm\discfarm) it says "Network resource not found"  This is
very
puzzling.  To recap, everything works perfectly on our local network.  
Clients can see the samba server and can attach.  We have a few clients that 
need access from a remote network to whom we are attached via an ATM 
circuit.  They can't see the samba server nor can they attach, even though 
they can see other Win9x/NT/2K boxes and can attach to those.  Is there 
something I'm missing?  Is this some limitation in samba?  We obviously have
the right ports open for IP, and the MS smb seems to be working just fine.  
Are there other ports that samba needs open through the router?  Please feel 
free to email me for more specific information at

russb@kfoc.net

I would post my smb.conf file here, but this is my first post to this list 
and I'm not sure if that would be too lengthy.  If needed I will post.  Here
are the quick and dirty server specs:

RedHat 7
intel system w/ SCSI disks
256MB RAM
samba version 2.0.7
Our network IP scheme:  172.20.0.0/255.255.252.0
Their network IP scheme:  10.0.0.0/255.255.240.0

We use SWAT to configure the server.  Thanks again for any help that you as 
a community can provide.


Russ