Can't connect to vncserver on dial-up network!

Mr. Wang
Thu Jul 10 05:04:00 2003

first, thanks for Scott C. Best's reply. I have asked for some help before.

Yesterday I made a test in my office,  The vncserver is still my office pc (win2000 pro), and the viewer is another pc(win98) in my office. 
Firstly, the viewer pc connect to the LAN via network card, the vncviewer can easily connect to the server. 
Secondly, I dial-up the viewer pc to the public Internet, it can't connect to the server,  neither telnet to the server 5900 port. I check my dial-up connection property----"banding TCP/IP protocol".
Thirdly, I asked my friend who is in another city connecting to my vncserver. He did successfully, and his computer(Win2000) connect to the LAN via network card. 

so draw a conclusion!*!*Winvnc can't be used on dial-up network!? why? it's not true in the vnc document. Who can explain that for me? 

Thanks in advance.