The Sidekick is a T-Mobile cell phone. To activate a Sidekick with AT&T service, you have to deactivate the phone’s SIM lock. The SIM lock is what restricts the use of the Sidekick to the T-Mobile network. To deactivate the SIM lock, you must obtain the unique SIM unlock code for your specific phone. This code is then entered into the Sidekick after installing an AT&T SIM card into the phone. Purchase an AT&T SIM card through the AT&T website.
Power down the Sidekick.
Place your fingernail inside the battery release latch, located on the bottom side of the Sidekick, to release the battery cover from its lock. Remove the battery cover. Remove the battery to gain access to the SIM card slot, which is located within the battery compartment.
Carefully slide out the T-Mobile SIM card currently installed in the Sidekick (if applicable). Slide the AT&T SIM card into the SIM card slot. The gold contacts, on the face of the SIM card, need to be face down. And the chip corner of the SIM card must face out of the slot. The card should click into place when it is properly inserted.
Write down the “IMEI” number printed on the label adhered to the inside of the Sidekick’s battery compartment. You will be asked to supply this number when you request the SIM unlock code for your Sidekick.
Reinsert the battery. Place the battery cover back on.
Obtain the SIM Unlock Code
Contact the T-Mobile customer support center at 800-TMOBILE (800-866-2453).
Request the SIM unlock code for your Sidekick. T-Mobile will provide the SIM unlock code for cell phones locked to the T-Mobile network to current and former customers for free, provided the following conditions are met:
If you are a current T-Mobile Postpaid Plan customer: You have completed a minimum of 40 days of active service with T-Mobile and your account is in good standing.
If you are a T-Mobile Prepaid Plan customer: You have completed a minimum of 60 days of active service with T-Mobile, your current account balance is at least $10 or you purchased a refill within the last 30 days.
If you are former T-Mobile customer: Your account is in good standing and T-Mobile has the unlock code for your phone or can obtain it from the phone’s manufacture.
Purchase the unlock code for your Sidekick from a commercial SIM unlock service such as Unlock All Cellular or Cellunlocker if you are unable to obtain the code from T-Mobile.
Unlock the Sidekick
Turn on the Sidekick with the AT&T SIM card installed. You will be prompted with a dialog box that says:
Title: Special Code Required
Dialog: Enter code to enable SIM
Box for Code: 1-8 digits
Options: Enable or Cancel
Use the Sidekick’s keypad to enter the SIM unlock code for your phone. A dialog box will appear stating “authenticating code.” Once the code is authenticated, the phone is unlocked.
Simultaneously press and hold the Menu key (top left or right side of the Sidekick) and “L” key if “Waiting for Activation Screen” appears on the display. If you are using a Sidekick 3, press and hold the “Del” and “L” keys instead.
Start using your Sidekick with AT&T service.