Hi. I'm trying to identify my phone via MAC Address or Phone Number in Android 11. I tried Taifun extension https://puravidaapps.com/wifi.php but it returns 02:00:00:00:00:00:00 for MAC Address. I tried Taifun extension https://puravidaapps.com/telephonymanager.php for Phone Number, but it returns nothing. Is Android 11 the problem? Any ideas to help me? I don't have much experience with Android and MIT APP. Thanks in advance.
Yes (short answer....)
You can generate a unique uuid for your installed app using this extension
Thanks for such a quick reply. I was breaking my head last weeks thinking what I was doing wrong... 
From android 10, it is no longer possible to read fixed numbers assigned to the phone. This is to prevent users from being tracked.
Use the Mac Bluetooth to identify the mobile.
A very good idea. Thanks. 
I checked the extension https://puravidaapps.com/bluetooth.php for reading Bluetooth MAC Address, but Taifu says it only works for devices < Android 8. Is this right?
Taifun, sorry...
well, what exactly is misleading in the documentation? App Inventor Extensions: Bluetooth | Pura Vida Apps
Returns Bluetooth MAC address for devices < Android 8. Starting from Android 8, the default mac address 02:00:00:00:00:00 will be returned.
Note : Starting from Android Oreo, the bluetooth mac address is only available to system apps. See also this stackoverflow answer.
follow @TIMAI2's advice...
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.
Here: http://kio4.com/appinventor/242_extension_bluetooth.htm
is an extension called com.KIO4_Bluetooh.aix
It has a block called MacBluetooth, although you actually get the Mac WiFi.
I have not tested it on Android 11, can you try it?
Sorry, Taifun, I wasn't questioning the technical information on your extension. Your work is excellent and it has been very useful to me. I was trying to tell Juan_Antonio, delicately (because he has been very kind with his answer), that, due to the information you included, his solution would not help me to solve my problem in Android 11. Greetings and thank you very much for your effort and work.
Sorry.
Well yes, I have tested it on Android 11 and, indeed, as Taifun says in its documentation, the result of the MAC is 02: 00: 00: 00: 00: 00.
In any case, thanks for trying to solve my problem.
Hi TIMAI2. As you say, your solution is the best to solve my problem and the only one possible at this time. Thank you for your work. All the best.
Well, I have tried the solution proposed by TIMAI2, but I have a problem. Using the V2 extension the blocks work correctly in Android 11 and they generate a kkuuid.ogg file with the UUID whenever I run the app from AI Companion. As soon as I generate the APK file, I get the message "The permission WRITE_EXTERNAL_STORAGE has been denied". Any ideas? Thanks.
As per the instructions, did you set the File scope to Legacy ?
Well, indeed, that was the problem. I am quite a newbie in this matter. Thanks again, TIMAI2.
Don't you worry, that fix is a new one on all of us!!
It is a comfort to know. I'm too old for these things... 
One of my first learning books : 
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