Share your experience!
Are you 100% sure that the phone was unlocked ?
Could you try a brand new SIM card? make sure to get the right size and not cut/trim it
The information that I got and assures me that the phone is unlocked, is the inrformation of SIM Lock Status = [ ] Network 0
I don't have one thing more than this 
I've tested with a brand new nano simcard with adapter, and a micro simcard that works fine on Iphone 4s.
I looked for a local support, but they recommends me to try a hard reset by PC Companion, but I've tried. And they sad that the phone doesn't supports my local carrier, but hey didn't know about my current carrier.
The information that I got, Brazillian carriers works with 700Mhz (Band 28), 1800 (Band 3) and 2600Mhz (Band 7).