While finding a "good paper" (likely meaning a reliable guide or working link) for this specific legacy chipset can be difficult due to outdated links, here are the current reliable options: SC7715 IMEI Tool (Legacy)

Using the SC7715 IMEI tool is when:

Because these devices often have lower build quality or unstable firmware, users frequently encounter "Unknown Baseband" or "NULL IMEI" errors after flashing a custom ROM or performing a factory reset. This is where the SC7715 IMEI Tool becomes necessary. sc7715 imei tool latest version

(sometimes labeled v2.0.1 or v2.1.0)