When phone numbers or dialing settings to an Internet Service Provider or a network change, you need to update the phone dialing options your modem uses to make a dial-up connection. You can use Phone and Modem properties in the Control Panel to add, edit, and customize phone dialing options on your computer for one or more locations. For example, you can change country, region or area codes, disable call waiting, and set up a credit card number to pay for calls. You can also set access rules for dialing local, long distance, and international calls. If you no longer use a dialing location, you can remove it.
Change Phone Dialing Options