Can I use my smartphone without installing the system? I only use my mobile phone to make phone calls and send text messages. How can I make my smart phone work like a normal mobile phone?

As long as you turn on your smartphone, it consumes more power than ordinary mobile phones. I suggest you use your mobile phone ROOT, then delete unused programs, and finally adjust the screen brightness of your mobile phone to the lowest level, and then turn off all data connections, such as GPS, Bluetooth and so on. The standby time will definitely increase a lot.