Hello. At once I apologize for the mistakes in the sentences since I use the Google translator. Over a year ago I bought an iPhone 5s. Everything was fine until I decided to restore it. It turned out that it is locked to the US t-mobile. I live in a small country, Belarus, which is located in the center of Europe. I have never been a member of the T-Mobile, and the offices are very far from my country. IMEI: 013990000276474 of my phone. I ask for your help. Yury
The phone you bought was never properly unlocked. It was jailbroken and hacktivated. When you restored, you lost the jailbreak and thus the hacktivation (which is essentially hacking the phone so that you can use other carriers without actually unlocking it).
In order to unlock, you'll have to use a 3rd party service. We cannot recommend one here. You could also try to seek redress with the seller, but with over a year having past, you're probably on you're own.
Need our help? Contact us.