Everything goes thru the x-rays at Santiago, porter or no porter. If you have a bunch of phones, keep them in your pockets. You would be surprised how many things you can fit in cargo pants and a suit jacket.
I was talking about SDQ. I have no idea how things work at STI but I would reckon a porter would certainly help. I would recommend one phone in your hold luggage, one in a handbag or a pocket. Spread them around like that.