From the Start menu, click Control Panel.

Under the Network and Internet section, click View network status and tasks.

NOTE: If you are viewing by icons, select Network and Sharing Center.

Select Connect to a network. 

Right-click on your dial-up connection and select Properties.

Select the box next to Use dialing rules. Then click Dialing Rules.

Highlight your location and click Edit.

Check the box next to To disable call waiting, dial:. From the drop down menu, select the call waiting code that is associated with your phone company or type in the code followed by a comma (i.e. 87#,). Click OK.

NOTE: *70 is the most common code used to disable call waiting. Please contact your local telephone company for the correct code to use and to assure that the access number that you are dialing is a local, toll-free call. We assume no responsibility for local toll or long distance charges incurred for the use of our service.

Click OK until all menus are gone. Reconnect your dial-up connection.