I dont know my samsung Gt-19300 imei

Samsung Galaxy S3 GT i9300: How to retrieve IMEI#:

To retrieve your IMEI #.. Here's several ways of doing it:

(1) The easiest way, on the phone call dial pad enter:
*#06#

(2) If you had cellular service on that device. Call your Service Provider for your IMEI #. They will have this available in their own records.

(3) If the phone was not activated on a cellular service yet, contact the Seller who sold it to you.. Many Sellers write down the IMEI # for their records.

(4) It could be on a label on the original box it came in..

(5) The other way to retrieve the IMEI # of that cell phone is to check your Google Account.. As long as you had set up your Google/Gmail account on your phone.

Here's how to do it:
On a computer internet browser, go to:
http://google.com/settings

Sign-in to your Google account and then select the "Expand All" tab which will list all your devices connected to your Google account and all of their IMEI #'s

TURN OFF YOUR PHONE..... REMOVE THE BACK COVER,
REMOVE BATTERY.... LOOK AT WHITE LABEL WITH I.M.I.E. NUMBER. WRITE IT DOWN..... REASSEMBLE PHONE. PUT THAT NUMBER IN YOUR CONTACTS UNDER IMIE, CALENDER OR NOTES TO YOURSELF... SO YOU WILL HAVE IT AT A PUSH OF A BUTTON.