Q: My phone is heating up considerably and cutting off while on a call- is this common

Hello Mark2501,

Welcome to the Apple Support Communities!

I understand that your iPhone is getting warmer than you would expect and shutting down. In this situation, I would first recommend reading over the attached article about keeping you iOS device within acceptable operating temperatures. If your iPhone is normally within acceptable operating temperature but is still shutting down due to heat, please let me know. 

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

Have a great day,

Joe