Online

• 1). Verify that the SIM card is inside your phone. If it's not, insert the SIM card into the SIM card slot inside the battery compartment.
  
  
• 2). Fully charge your Nokia 6555 phone.
  
  
• 3). Remove the battery from your Nokia 6555 phone and locate the serial number (ESN) on a sticker inside of the battery compartment. Write the number down.
  
  
• 4). Go to AT&T's phone activation web page (see Resources).
  
  
• 5). Select whether you are a new customer, upgrading your phone, adding a line or activating a pay-as-you-go device.
  
  
• 6). Enter your Nokia 6555 phone number into the appropriate fields.
  
  
• 7). Confirm your identity by entering your billing ZIP code or the last four digits of your Social Security number.
  
  
• 8). Click "Next" and enter the serial number (ESN) from your mobile phone in the appropriate field.
  
  
• 9). Click "Activate"; restart your phone if prompted.
  
  

By Phone

• 1). Verify that the SIM card is inside your phone. If it's not, insert the SIM card into the SIM card slot inside the battery compartment.
  
  
• 2). Fully charge your Nokia 6555 phone.
  
  
• 3). Remove the battery from your Nokia 6555 phone and locate the serial number (ESN) on a sticker inside of the battery compartment. Write the number down.
  
  
• 4). Contact AT&T's customer service department at 800-331-0500 from a land-line phone or by dialing 611 on your Nokia 6555. Follow the prompts for activation.
  
  
• 5). Provide the representative with your mobile phone number, your name and your billing ZIP code or the last four digits of your Social Security number.
  
  
• 6). Provide the representative with your mobile phone's ESN number.
  
  
• 7). Wait for the activation process to be completed. Restart your phone if prompted.