Q: Iphone 5 -16GB, i have 2 problems with it 1- for many times it's temperature gets too high and it says the phone needs to cool down ? 2- again manytimes the phone power off during the call

Howdy Fabrecio,

Welcome to Apple Support Communities.

If I understand correctly, you're running into an issue with your iPhone 5 displaying a temperature related alert message and the iPhone is also turning off unexpectedly. 

This article provides a lot of great information about iPhone operating temperatures, which should help you understand why the alert is appearing and resolve any temperature related issues:

Keeping iPhone, iPad, and iPod touch within acceptable operating temperatures - Apple Support

The article below outlines troubleshooting suggestions that will resolve issues with iOS devices turning off or restarting unexpectedly.

If your iOS device restarts or displays the Apple logo unexpectedly - Apple Support

So long.