AT&T

• 1). Call AT&T by dialing "611" from your cell phone, or log into your online account.
  
  
• 2). Sign up for AT&T Smart Controls. A $4.99 charge per phone line will be added to your monthly bill.
  
  
• 3). Navigate to Smart Controls from within your account online.
  
  
• 4). Enter the numbers to block; you are limited to 10. This will block texts and voice calls from the numbers you entered. Within 24 hours, messages from those numbers will be blocked.
  
  
• 5). Remove the numbers you want to unblock from the same section. Save your changes.
  
  

Sprint

• 1). Open up a new text message.
  
  
• 2). Enter "9999" into the "Send to phone number" box.
  
  
• 3). Type "Block" and the phone number you want to block in the body of the message. For example "block 5551234567" will block the phone number 555-123-4567.
  
  
• 4). Click "Send" to send your message and finalize blocking the number.
  
  
• 5). Type a new message to 9999 with "Unblock" and the phone number to unblock from your list, and click "Send."
  
  

Verizon

• 1). Navigate to Verizon Wireless' account management page, and log into your account.
  
  
• 2). Select "Preferences," and choose "Text Blocking" from the menu on the left.
  
  
• 3). Enter up to 10 numbers to block, and select "Save" to save your changes. These numbers will now be blocked. You will also have the option of removing numbers from your block list here to unblock them.