2. Choose the service: the number of codes / price / terms
At this stage, we already know exactly what code we need - NCK or RGCK. So when choosing a service, pay attention first of all to the number of codes in a particular service (whether the required code is there).
It is important to know that codes are usually provided with "kits". If the service says that it provides several codes, it is impossible to order one of them separately, for example, only RGCK or only Unfreeze. But there are services that provide only one NCK unlock code, they are cheaper than services that provide codes of all lock levels. Thus, the price for a service primarily depends on the number of codes, as well as on the timing of the order.
But we recommend, if possible, to choose a service that provides codes of all lock levels. The unlock codes are always correct. In case unlock is not successful, and you had all the existing codes for this IMEI, you will know exactly: the reason should be searched in the phone and its firmware. If you had one code, you will not know where to look for the problem. Perhaps you just did not have the necessary code (PROVIDER, SUBPROVIDER or Unfreeze).
Codes for Samsung, depending on the service, can be requested from the operator (only NCK code) or from the manufacturer's database (2 or more codes). But whoever was the source of the codes, the codes everywhere will be the same. There are cases when there are no codes in the database when requesting through different services and the client receives a response - "Not found". If you received such an answer, it is unlikely that you will be able to get the codes for this IMEI on another resource.
To unlock the phone for which there are no codes, it is possible through the cable with the help of special boxes for unlocking [Z3X, Octopus, Medusa, Infinity BOX]. But this unlock is carried out directly in the service centers, and not remotely.