*57 is a call tracing service offered by most phone companies. It allows you to easily trace calls made to your phone number. Essentially, *57 records the calling number and other identifying information such as the date and time of the call.
Call Block, otherwise known as Call Screening, is a feature that allows you to block calls from up to 10 phone numbers within your local calling area for a low monthly rate. Turn on: Press *60.
Pick the phone up and at the dial tone, press *66. If the line is free, the call will go through. If the line is busy, you may hear a message. The feature will retry the line every 60 seconds for the next 30 minutes.
Anonymous Call Rejection (*77) stops calls from people that use a blocking feature to keep their name or number from being displayed. When Anonymous Call Rejection is turned on, callers will hear a message telling them to hang up, turn off the blocking feature, and call again.
*31# (Disable Caller ID)
If you want to keep your privacy and prevent others from knowing when you call them, you can disable caller ID by using this code.
This Vertical Service Code, *82, enables calling line identification regardless of subscriber preference, dialed to unblock withheld numbers (private callers) in the U.S. on a per-call basis.
Block calls from your phone
Press *80 to turn call blocking off. Press *60 to turn call blocking back on.
Dial the code *92. Enter the 10-digit phone number forwarding number. Dial the # key. You will hear a confirmation message.
*#67# – Display call forwarding information on your phone. *#61# – See how long it takes to forward calls.
*#62 is a short code that can be used to check whether your calls have been redirected or diverted without your consent. It does not, however, work on all Android phones.
When you call a number and the line is busy, hang up the receiver. Pick up the receiver again and press *66. You will hear a recorded message confirming that the line is busy, and Busy Call Return will alert you when the line is free. Hang up the phone again.
*67 - Caller ID Block: Hides your phone number on Caller ID systems. *69 - Call Return: Redials the last number that called you. *70 - Call Waiting: Places your call on hold so you can answer another.
Screen incoming calls and only accept calls from certain numbers. Other callers will hear a message that you are not accepting calls at this time. To activate, dial *64.
The moment you dial *67, your phone sends a signal to your provider requesting a caller ID block. From that point forward, your outgoing calls become shrouded in mystery, appearing as "private" or a "blocked number" on the recipient's end.
Star 69 refers to "last-call return," the Calling Feature Vertical service code *69 keyed on a landline telephone set in order to return the call of the last one to ring (in Canada and the United States).
Key hardware info: *#0*#
When you enter *#0*# into the phone's dialer, the device enters service mode and brings up a diagnostics menu.
The *#9900# code is a diagnostic mode code for Samsung mobile devices. It can be used to access a variety of system information and diagnostic tools, such as enabling/disabling fast dormancy, logging options, and system dump mode.
For a Google Pixel, dial *#06# on your phone's keyboard to get the IMEI number. For phones with a removable battery, some IMEI numbers are listed on a sticker under the battery on the back of the phone.
Dialing *68 will disable the Caller ID for the next outbound / external call only. Selecting a line and dialing this feature code will result in a prompt on the phone display as well as an audible message: "Caller ID is BLOCKED for the next outbound call only."
*63 Activation, *83 Deactivation - Selective Call Forwarding - Allows the subscriber to have incoming calls from a limited number of calling parties forwarded to a prespecified remote station.
The next time you receive a call from a number you wish to block, end the call and dial *97. The number will automatically be added to your Selective Call Rejection list. You can block up to 100 numbers.