A SIM is the most essential tool to be inserted and get started with making calls through cellular network. A SIM also provides internet services when you are not nearby any wireless network services. The SIM card connector in the phone is comprised of the small slot which has a space of inserting the SIM and it is connected through multiple receptacles in order to receive conducting terminals. The iPhone 6s comes with a NANO SIM card holder which is by far the smallest in size but stores and provides same amount of data as the older versions. The understanding of SIM card holder functions can be technical and with these technicalities come the threat of damage to the SIM card holder and the connections it has into the phone which can result into a completely non functional SIM card.