Is there by any chance a shield that can take an 4G LTE compatible SIM card activated by a carrier and establish a connection?
Googling "4g shield arduino" gave this. It will need a 4G LTE capable SIM, but I guess "it depends" if any 4G LTE SIM will work..
This is a really old post but I also found this LTE shield which is much cheaper than the cooking hacks one.
Be carefully; this module is a dual band only (900/1800 MHz); no 850 or 1900 MHz.