Is a domain name required for accessing a personal "web site"?

From: Mark Harton (mharton_at_pageservices.com)
Date: 06/29/04 

Date: 28 Jun 2004 16:02:34 -0700

I have personal web pages served by Apache on RedHat 9. I'm able to
see these pages on other PCs in my home using the server's IP address
of 12.xx.xx.xx. All of the PCs including the server are simply
connected via a hub. The hub is connected to a DSL modem. Currently
there is no firewall, as I'm trying to solve the problem below first.

I would like to be able to access my web pages using a standard web
browser (from work, from friend's homes, etc) simply by typing in the
http://12.xx.xx.xx address WITHOUT having to have a domain name (
without having to use noip.com, either). The IP address is dynamic,
but I have an SMS script that keeps me up to date as to what it is.
The several help and howtos that I've read through on
VPN/tunneling/masquerading all refer to DNS and using a registered
domain name. Is there a way to access a home Apache server via a web
browser that is external to the LAN using an IP address, not a
registered domain name?

Any help or HOWTO re-direction would be greatly appreciated.