I had a spare Pantech P2030 from AT&T that was locked due to some SIM problem. But I was afraid to fidget with it since I am in India and it was purchased in the US. Researched about it on the Internet and landed up at Unlock Your Phone for Pantech phones. Entered the IMEI and it flashed the Unlock code on the screen, without going through any tiresome procedures or displaying an array of annoying ads.
I simply typed the Unlock code received and Voila!
The phone was unlocked without any retry attempts.
Using VodafoneIN GSM SIM and it's working just fine, without any problems.
It's hard to come across a hassle-free site online that really helps you resolve SIM blocks.
But this site is surely an exception!