First thing you need to do is to Double click on My Computer
... Note Every Click unless mentioned will be with the Left mouse button.

Then Double Click Dial-Up Networking

Click on More and then click on Edit Entry

That will bring up a menu. click on Properties. That will bring up a screen where you can change the phone number.

You will need to replace the number you see here with the new, national access number. You can find a new number by browsing our National Dial-Up search page.
If you need to dial *70 to disable call waiting or a specific number
to access an outside line, leave that before the number.
PressEnter does not provide
nor does it charge customers for telephone service, and under no
circumstances will PressEnter pay customer telephone company
charges.
If the number you select is not a local call then you are
responsible for any telephone charges.
Click Ok. When you Dial you will want to change the username to
username@pressenter.com and hit Dial. When it dials it will save that.
You are done.