Looks like Apple's currently fixing their activation servers. But the good news is that previous tickets gotten via SAM trick still work.
what it boils down to is an incorrect assumption on the part of the ticket server, which is why it was so quick to fix
for the next few hours, trying SAM on new SIMs will probably be hit or miss, but eventually it will be all "miss"
You can find the iClarified tutorials on how to unlock your SIM below:
● How to Unlock Your iPhone Using SAM [Easier]
● How to Unlock Your iPhone Using SAM [Original]
● How to Backup Your Unlock Ticket [iFile]
● How to Backup Your Unlock Ticket [RedSn0w]