On the dialing screen, press [#][*][menu][right arrow] and confirm.
If your phone does not have a SIM card should continue pressing the [arrow right] key until you see "IMEI [0]" The screen will display the first 7 digits to see another 7 scrolls down. To get the full 15-digit number you must added at the end of the digit 0.
IMEI numbers either come in a 17 digit or 15 digit sequences of numbers. The IMEI format currently utilized is AA-BBBBBB-CCCCCC-D: