I installed IOS 12.3.1a on a 2611 I have.
Configured ITS as per the documentation.
If I try to access http://x.x.x.x/Telephony-service.html
I get back "Page can not be displayed"
As a test I tried http://x.x.x.x/logohome.gif and was prompted for the webadmin username and password and the gif came up in the browser.
Any thoughts? I checked the security settings in my browser and it all looks ok.
Scott