I some times will try to make a call and iPhone6 locks up.

[digitalcuriosity]

OK, I should have expanded. The symptoms you described were something I experienced when I had a jailbroken and hacktivated iPhone years ago.

It was a nightmare. Never again.

I have read of the problems others have run into when jail breaking their phones.

Since i am renting my phone from Sprint, i would never do anything to it as jail breaking.

 

[brixtonboy]

The simple answer would be is to give it back to them, and explain your problem. Job done. Customer Service