Why do cell phones don't really turn off (unless battery removed)? I've known this for a long time.
A quick google confirms that many people think the same.
Basically, that when shutting down a cell phone, the antenna still communicates with the tower. Triangulation will still work, as well as some other stuff.
Only when the battery removed, is a cell phone &quot;really&quot; shut down.
Not that I care but it's interesting to know why!
If possible, please provide primary sources - it's time to shut all the myths around this down!
Update, the following question has been suggested:
What is the fastest way to shutdown unrooted Android phone?
Obviously, this is semantically NOT equal.
The answer there, despite being a very detailed answer, does not provide the reason WHY the baseband processor remains ON.
For a technological feature to exist on perhaps Billions of devices, there must be a need for that... Especially since it drains battery and costs cellular tower bandwidth.
A telephone that is not in contact with the local cell phone tower cannot detect an incoming call.  When someone places a call to your phone,  you probably want to get notified that your phone is ringing, even if you have hit the power button.  The power button turns off the display,  but doesn't actually shut down the phone.
Being in communication with the tower uses some battery power.  It's quite low,  but it isn't zero.
This is true for a smart phone, and also for a dumb phone.  A cell phone of 20 years ago also used battery to maintain contact with the tower.
Addendum:  When I tap the OFF button on my phone,  it goes into Standby mode.  The screen goes dark, and I have to enter a password before using it again, mostly.  But it still can accept incoming calls, and it alerts me when one comes in.  When I go through the POWER OFF procedure,  and somebody calls my number,  they receive a notice from the phone company that my phone cannot be located.  I do not know whether baseband operations are still drawing current.