To download the firmware for the Nokia C1 (TA-1165) you specifically need a because this device runs on a Spreadtrum (SPD/Unisoc) SC7731E chipset
PAC stands for PacRom Archive or Download Agent File, proprietary to MediaTek-powered devices (which the Nokia TA-1165 is). Unlike standard .zip OTA updates, a PAC file is a complete, low-level firmware package containing: nokia ta-1165 firmware pac file download
Summary
Settings → Device information → Software update for official OTA updates.Conclusion