Android: getDeviceId() returns an IMEI, adb shell dumpsys iphonesubinfo returns Device ID=NULL

问题

Different results for my low cost chinese tablet. It's not a phone so why getDeviceId() returns a number that seems to be a valid IMEI?

C:\>adb shell dumpsys iphonesubinfo
Phone Subscriber Info:
  Phone Type = GSM
  Device ID = null

but using

TelephonyManager tManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
String uid = tManager.getDeviceId();

uid = 35881700... (I'm not showing the whole IMEI number for privacy)

来源：https://stackoverflow.com/questions/11518113/android-getdeviceid-returns-an-imei-adb-shell-dumpsys-iphonesubinfo-returns