NT won’t share na internet connection

This is the deal:

We have a client who had ISDN through one ISP and wanted to switch to another ISP. So we:

Checked out the config on the Ascend 15 (i know it’s old)

Made a new connection in Dial up Networking, got the server online-kewl Unfortunately ONLY the server could get out. None of the other settings were changed, just the number the modem was dialing…nothing. Anyone got a clue as to what happened?

TIA–JC