VNC Host Service behind a dial-up connection

[Railroad]

Hello -

I have a client in the Saranac lake region - way out in the country - 
and he has a dial-up connection tot he Internet.

I'm trying to provide VNC support to him.

He has VNC 3.3.7 running on his WinXP laptop and configured with Host 
running as a service, and can use the VNC Viewer to get out to his 
Office.

When his is On-Line I've given him a link that shows his WAN IP through 
the MSN ISP service - but I cannot gain access to provide the support 
he needs.

What is happening in this situation??

How can it be patched or must we fall back to pcAnywhere to have the 
support service available??

Thanks,

RR