iPhone 6 plus randomly crashes help

hi I've had my iPhone 6 plus for a while now and recently it started crashing on its own it would randomly reboot on its own when I'm on a phone call it texting about anything it just would randomly crash

iI've also had issues with it freezing up on me multiple times any help?

I Always set up my iPhones as new so I didn't use a back up

tthe strange thing is that my if I'm on a phone call and it crashes it doesn't hang up the call as the phone reboots it will hold the call and I'm still on the phone even though it crashed and it's showing the apple logo as its rebooting

i dot know exactly what's going on but it happens randomly and its really annoying