There is no software that "calculates" an NCK code from an IMEI for free for STC devices. Legitimate unlocking services require access to manufacturer databases (Huawei, ZTE, Alcatel) which cost money.
The representative explained that the NCK (Network Control Key) code was a security feature to prevent unauthorized use of the SIM card on other networks. Ahmed was told that he needed to contact STC's customer support to obtain the code. Stc Quick Net Nck Code
There are several ways to obtain an NCK code for STC Quick Net: There is no software that "calculates" an NCK