On a phone, *69 (Star 69) is a call return service that automatically dials the last number that called you, allowing you to call back someone who didn't leave a message or called from a private number, though it's largely a landline feature for North America and less common on modern cell plans. It works by connecting you to the last incoming caller's number, even if they blocked their ID, but it may not work if you have voicemail or if the carrier restricts it.
Dialing \*69 on a landline or mobile phone (where supported) automatically redials the last incoming number, a feature called "Call Return," allowing you to connect with the last person who called you, even if they had a blocked ID, though it's less common on smartphones with robust call logs. You just pick up the phone, listen for the dial tone, press *69, and it will either connect you or tell you the number.
Dialing *67 before a phone number hides your caller ID, making your number show up as “Private” or “Blocked” on the other person's phone. It's a quick and easy way to keep your number confidential, whether you're using a landline or mobile phone.
The person you blocked will not realize you blocked them when they try to call you. On their end, they'll hear the phone ring a few times. Then, their call will go straight to voicemail. Here is the one big catch with blocking someone on iPhone: Technically, they can still send you a voicemail.
• *70 Disable Call Waiting Per Call
number.
To deactivate the No Answer/Busy Transfer feature, just dial *73.
Dialing *57 on a cell phone activates Call Trace, a service that records the phone number of the last incoming call, primarily for reporting harassing, threatening, or obscene calls to law enforcement; it's a paid, per-use feature that logs call metadata for police investigation, not for your personal number display. You must use it immediately after hanging up a malicious call, and your carrier sends the information to the police, not directly to you, after you file a report.
Activate Incoming Call Barring: Dial *35*0000# to activate barring of incoming calls. Bar All International Calls: Dial *331*0000# to bar all international calls. Bar All Incoming SMS: Dial *35*0000*16# to bar all incoming SMS. Deactivate All Barring: Dial *330*0000# to deactivate all types of call and SMS barring.
You should avoid answering calls from unfamiliar international area codes often used in scams like 268, 284, 473, 649, 809/829/849, and 876, as well as some domestic ones like 216 (Cleveland), 469 (Dallas), and 712 (Iowa), to prevent one-ring scams, callback fraud, and other fraudulent schemes; letting unknown calls go to voicemail and searching the number is a safer strategy.
*98 Group Call Pickup Enables you to pick up calls within an assigned call pickup group. The call pickup group is determined by an administrator. When you dial the call pickup code, the ringing phone in the group is answered.
Dialing 1471 on a UK landline (and similar services in other regions) tells you the number of the last person who called you, allowing you to return the call by pressing '3' (for a charge) or simply noting the number, though it won't reveal withheld numbers (prefixed with '141'). Separately, SCP-1471 refers to "MalO ver1.0.0," a fictional, creepy mobile app from the SCP Foundation universe, known for its unsettling imagery and ability to bypass app store security.
Block individual numbers on Android
If you're with T-Mobile, you can also use #662# to block all suspected spam calls on your Android.
Call Retrieve Used to retrieve a parked call. Enter *88 followed by the extension that call is parked against. If the call is parked against your own extension, press the # key.
🔐📞 ##002# instantly cancels all call forwarding on your phone — busy, unreachable, or no-answer. It's a simple way to reset settings and protect your privacy. ✅ Just dial ##002# and hit send.
*64 | All Other Callers: Block
All other calls (not otherwise specified in Call Handling settings) will be blocked.
There's no single code to confirm a hack, but dialing *#21# checks for general call/message forwarding, *#62# shows where calls go when unreachable, and *#002# disables all forwarding; these codes reveal suspicious activity like call diversion, a common sign of compromise, though they don't detect malware.
a YouTube video explains how to check Android phone for hacks, while a Norton blog post provides a list of codes for this purpose.
The code *#0*# unlocks a secret hardware diagnostic menu on most Samsung Galaxy phones, allowing you to test the screen (colors, touch), speakers, sensors (like proximity), camera, and other components without needing special apps, acting as a quick way to check the phone's health before buying or for troubleshooting. This menu appears automatically in the phone's dialer and offers various test modes for different hardware parts, but note that on newer models, a different code like *#*#88#*#* might be needed, say some YouTube Shorts.
The owner of the blocked number won't get notified, but if they try to contact you, they might see signs such as calls not going through for a long period, the SMS delivery status showing their messages as undelivered, or the status not showing at all, depending on which SMS app and phone they're using.