Default [Q] UMTS MAIN MENU not exits

Hi all,

I'm trying to unlock AT&T Samsung Galaxy S4 SGH-I337 following the procedure mentioned in

But unfortunately at step3 mentioned in the procedure, the UMTS MAIN MENU is not showing up, where upon I'm unable to proceed further to unlock the device.I had inserted some valid SIM card other than AT&T as I don't have that SIM card.

Please note entering *#27663368378# is not taking to DEBUG SERVICE MENU.

Please suggest workable solution.