Windows Live Messenger

• 1). Click "Start." Type "Windows Live Messenger" in the search box at the bottom of the "Start" menu. Press "Enter." Sign in to the application with your user name and password.
  
  
• 2). Click the "Add a Friend" icon next to the "Inbox" button. Select "Add a Friend" from the drop-down menu. The icon looks like a person with a plus sign on the right.
  
  
• 3). Move the cursor to the text box under the "Enter a Mobile Phone Number" section in the dialog box. Type in the recipient's cell phone number, including the area code, like so: "800-555-1212." Click "Next." Select "Close" on the "You're Done" page.
  
  
• 4). Double-click on the recipient's phone number in your list of contacts in Windows Live Messenger. Type a message in the text box, such as "This page was sent from my computer. Call me back at 800-555-2222." Press "Enter."
  
  

Yahoo! Messenger

• 1). Click "Start." Type "Yahoo Messenger" in the search box at the bottom of the "Start" menu. Press "Enter." Sign in to the application with your user name and password.
  
  
• 2). Click "Actions." Choose "Send an SMS Message" from the drop-down menu.
  
  
• 3). Click "Other Contact" in the dialog box. Type the recipient's cell phone number in the blank text box, including the area code, such as "800-555-1212." Click "OK."
  
  
• 4). Type a message to the recipient, such as "This page was sent from my computer. Call me back at 800-555-2222." Click "Send."