Here is my story.
I bought an iPhone 5S locked to AT&T USA from 2013. I've been using it about ~1 year with heicard SIM. Generally, everything simple functions work fine. But there are still some trouble with Contact list, iMessenger, Facetime... So, I decided to officially unlock my iPhone 5S AT&T to make it works without using heicard SIM
I tried to find out how to Officially unlock iPhone, after some research on Google. I found this site: https://unlockiphoneofficial.com
Everything looks cool. They said they can unlock my AT&T iPhone permanently via iTunes. At first, I thought that's scam, but after check that site. They accepted PayPal for payment and offer 100% money back. A lot of satisfied customers with their good reviews. Ok, I think if they accept PayPal, if this is a scam, I can open a dispute to get my money back. And finally, I placed my order and completed my payment. I received an email for order confirmation. And as they said, this unlock may take about 1-6 days.
I wait for this unlock day by day but at the day 6, my iPhone still not unlocked. I have a bit doubt with this company and I tried to contact them. They told me they didn't work in weekend, so the timeframe may can delayed for 1-2 days.
Ok, I leave it and keep waiting. And wonderful ! At the day 8, I was received an email notice that my iPhone has been unlocked ! Immediately, I connect my iPhone to iTunes to complete the unlock with their tutorial in email. And, boooom, iTunes said: "Congratulations your iphone has been unlocked". It's really unbelievable ! My iPhone is now working!
After that, I sent them an email to give my thanks and I said I will recommend my friends and ask them about Affiliate system. And awesome ! They helped me to enable affiliate functions in my account. And here is my Affiliate link:
If you're going to unlock your iPhone :D Please click to my affiliate link.