Mining on GPUs is already pretty much unprofitable. Mining on a cell phone is just pointless mate. These things can also run really hot really fast. Sure, you could place a fan in front of your cell phone(s) to cool them, but that's like 40W of electricity you will spend cooling those devices that will barely bring in a cent.

Here's a better idea: cell that cell phone or those cell phones you have and buy BTC or ETH with the cash you get. You'll thank me later.