For the development modem, I’ve chosen a simple SIMCOM SIM5360 3G modem. Just something to get us started with. The board we are making will also support a SIM7100 4G modem chip as well. Most recent SIMCOM modules are compatible. Specifications for the modem are here: http://simcomm2m.com/En/module/detail.aspx?id=82 <http://simcomm2m.com/En/module/detail.aspx?id=82> There are three models available: SIM5360A Dual-Band UMTS/HSPA+ 850/1900MHz SIM5360(J)E Dual-Band UMTS/HSPA+ 900/2100MHz SIM5360J(D) Dual-Band UMTS/HSPA+ 800(850)/2100MHz The 2G frequencies are all quad-band (GSM/GPRS/EDGE 850/900/1800/1900MHz). The only difference is the dual-band UMTS/HSPA+ frequencies 850/1900MHz, 900/2100MHz, or 800(850)/2100MHz. Hong Kong uses: https://www.frequencycheck.com/carriers/csl-hong-kong <https://www.frequencycheck.com/carriers/csl-hong-kong> Name Interface B1 (2100) <https://www.frequencycheck.com/bands/umts-hspa-band-1-2100> UMTS <https://www.frequencycheck.com/interfaces/umts-hspa> B8 (900 GSM) <https://www.frequencycheck.com/bands/umts-hspa-band-8-900-gsm> UMTS <https://www.frequencycheck.com/interfaces/umts-hspa> So, the first development modem I am getting is SIM5360(J)E. For other developers, who will be wanting early OVMS v3 modules, where do you live, what cellular carrier do you use, and what frequencies do you use? Regards, Mark.