I am playing with a https://wiki.eprolabs.com/index.php?title=SIM_808_GSM_GPRS_Module for an Arduino project that I am working on. It was advertised online as supporting 4G but when I try a sim (Skinny) on a 4G network it does not appear to register. Another sim (Vodafone) does register but I don't think its a 4G connection.