ICS will work with dial-up.  I have used it in the past quite successfully before we had access to DSL.

I would start with using a MS-DOS prompt and issue an IPCONFIG /all command.  All of the computers should have a compatible IP address assigned and should be in the group of 191.168.0.xxx where the computer with ICS activated would be assigned 1 and the other systems assigned an address of 2 to 254 for the xxx in the IP address.  The gateway and DNS IP addresses should be 192.168.0.1 for all the systems other than the ICS system and that should have the address assigned by your ISP once you are dialed in.

If that checks out, then do a ping from one of the systems other than the ICS system to 192.168.0.1 and verify it does not timeout.  If that is successful, then do a ping to a known network address, such as ping freepctech.net and see if that can be resolved and accessed.  If it cannot be resolved, then there is something wrong with the DNS configuration.  Try the same thing from the ICS computer to verify it is connected correctly and can reach the DNS assigned.

This should get you started to look at where you are misconfigured, or have something missing/wrong.  Let us know where it fails.

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