Hidden Battery Power / Boost Signal Strength By pressing *3370# or #3370#, you'll activate your phone's “reserve battery power”. Battery life will increase by 50%.
iPhone code: *3370#
If you ever find yourself somewhere getting poor cellphone reception, type in this code to turn on “enhanced full rate” mode. EFR mode improves your cell reception, but your battery life might be compromised.
*#67# (Check Call Forwarding)
If you want to know whether your calls are forwarded to another number, use this code. That'll tell you whether call forwarding is active on your device, and it'll also show you the number your calls are being forwarded to.
Instead, #3370# or *3370# enables Enhanced Full Rate Codex, improving sound quality at the expense of battery life - which you will recognize as the exact opposite of what the myth claims the code does. The real code for improving battery life by reducing sound quality on some phones is actually *#4720#.
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.
Once your wi-fi and LTE are off, pull up your phone's keypad as if you intend to call and dial the following: *3001#12345#* followed by the Call button. This should take you to the field test display and give you several options such as your SIM info, serving cell measurements, and your connected mode.
In Android, dialing *#21# is not recognised as any USD code or any IMR service. As you dial it, it will connect you as a normal call and rejects it because this ohone number is not linked or not associated with any business or government services. It doesn't do anything.
Check Your iPhone's Signal (*3001#12345#*) To check how much signal your iPhone has, enter Field Test Mode by typing *3001#12345#* on the keypad. This allows you to check all the details about your iPhone's signal, such as settings, network, and other technical data.
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. This information can then be used to request a complaint with your phone provider or to report the call to law enforcement.
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.
Call forwarding is often enabled by dialing *72 followed by the telephone number to which calls should be forwarded. Once someone answers, call forwarding is in effect. If no one answers or the line is busy, the dialing sequence must be repeated to effect call forwarding. Call forwarding is disabled by dialing *73.
Dialing ##002# deactivates any conditional or unconditional call forwarding settings on your account and also deletes any data such as messages or voicemails that were previously diverted to another number. This code only applies to phones on GSM networks such as AT&T or T-mobile.
IS 3370 (Part 2): 2009 which covers the 'Recommendations for design of concrete structure for storage of liquid' was published in 1965. The code was split into four parts. Part 1 contains provision that is general in nature and applicable to plain, reinforced and prestressed concrete.
Key hardware info: *#0*#
When you enter *#0*# into the phone's dialer, the device enters service mode and brings up a diagnostics menu.
Disable call forwarding on US Cellular
Disabling call forwarding on US Cellular network is as easy as running a USSD shortcode. Open the Phone app on your Android device. Enter *720.
If you want to know if your Android phone is being tracked, look for performance issues such as a rapidly depleting battery or an unusually hot phone. Here's how to check for performance issues that could indicate your phone being tracked: Open Settings > Battery and device care. Tap Battery > View details.
Check Call barring
Call barring lets you block incoming or outgoing calls to and from your phone. This may be useful if you keep receiving unwanted telemarketer calls or want to avoid expensive international calls. To check if the feature is enabled on your device, dial *#33#.
Accessing Field Test Mode on an iPhone can be quite straightforward: simply go to your phone's dialer, type in *3001#12345#* and hit the dial button. Unfortunately, though, you often can't get reliable signal strength (RSRP) or signal quality (SINR) readings on iPhones.
In 4G LTE and 5G networks, signal quality is measured as SINR. Increasing your SINR can have a dramatic impact on your connection speeds. The best way to improve SINR is to use a directional outdoor antenna, either connected to a signal booster or directly to an LTE or 5G hotspot.