How to get phone number from an incoming call?

Question

How do I get the phone number when there is an incoming call in Android?

Answer 1

The answers above are right, but, don't forget about permissions
<uses-permission android:name="android.permission.READ_PHONE_STATE" />

NOTE, starting form Android 9 to read incoming call number you have to request this permission
<uses-permission android:name="android.permission.READ_CALL_LOG" />