I ordered only the wifi module for my smart car and have it setup and working great. I didn't order the modem module as I didn't want another cellphone bill. Can someone give me an idea of what a monthly charge might be for this and is it a special carrier that deals with this type of device. Also if I order the modem module now will it come with a sim. I just don't want to order and find out the monthly cost is too high. Thanks in advance.