The android.telephony.TelephonyManager class provides information about the telephony services such as subscriber id, sim serial number, phone network type etc. Moreover, you can determine the phone state etc.
Android TelephonyManager Example
Let's see the simple example of TelephonyManager that prints information of the telephony services.
textview from the pallete, now the xml file will look like this.
Now, write the code to display the information about the telephony services.
You need to provide READ_PHONE_STATE permission in the AndroidManifest.xml file.