SIMPIN1??

I was playing around with my phone yesterday and came across something that said to enter my SIMPIN. I had no idea what this was. It's an 8 digit code and I tried a few things I thought it might have been. Now my phone is locked. Obviously, this wasn't one of my smarter moves, I should have left it alone. But anyway, now I can't get into my phone, which is proving problematic. 

Here's what happens when I turn my phone on:

A little message block pops up and says: "SIM Blocked"

It gives me the option to "Unlock" which then takes me a block titled: "PIN1 Unblock Code"

The PIN1 Unblock Code is supposed to be 8 digits long and it accepts any combination, the problem is the next 2 screens

After entering in any 8 digit code combo, I am taken to a screen that says: "Enter New SIM PIN"

Once again, any combo is accepted

Then I am taken to a new screen that says: "Re-enter New SIM PIN"

Now, logically, I feel that it should accept the same 8 digit code I just entered, but of course it doesn't.

Instead a little message pops up that says: "Code invalid. Try again."

Then I am taken back to the original SIM Blocked screen.

Any help? AT&T stores aren't open on Sundays and neither is their customer service hotline. It's pretty important that I get my phone in working order ASAP as this is my only form of communication (I don't have a home line).

Thanks in advance to any advice that you can give me!