How to find the phone number in android?

[aptgopal]

Hi
Any one help me to do this .I want to find the mobile number using in the particular android mobile programmatically

I tried the following
TelephonyManager tMgr =(TelephonyManager)this.getSystemService(Context.TELEPHONY_SERVICE);
String mPhoneNumber = tMgr.getLine1Number();
It is working fine in Emulator but It is not working in my phone

How to do that

Thanks in advance