For the 4G modem options we need to go through FCC, CE, and ROHS certification. Minimising/eliminating the changes to the main board simplifies this (and brings down the exorbitant costs) but if there is anything urgent / necessary, now is the time to do it. The goal here is to maintain 100% compatibility with existing OVMS main boards, to keep this is a simple and relatively cheap upgrade of the modem board. So far, I have come up with this minimal list: Main board v3.3: Improve soldering of micro USB port. Bigger solder pads, and more solder to secure it better. Modem board v1.3: Add support for SIM7600 module. Modem board v1.3: Fix support for DTR sleep/awake support. Is there anything else required for this update? Regards, Mark.