To remove Port Number in URL

Question

HI ,
We have an application which uses asp pages.
when i run the application The Url is http://localhost:PortNumber/MyApplication/login.asp, An error is displayed saying that The page is not served.
When i remove the Port number from the Url, it is working fine.
Is there any other way to remove the Port number from the Url permenently. 
Thanks in Advance.