ZTE Axon Mini suddenly double beeps during calls

[AC Question]

I've had my ZTE Axon Mini for a few weeks now. I haven't changed any settings since I initially set it up, and all of a sudden it started double beeping about every minute during phone calls yesterday. When I looked it up online I read something about minute minder call settings, but I can't find any such call settings on my phone anywhere. Please help! It's driving me CRAZY!