first, upgrade to ros7.1beta2 on what EM12-G works perfect.
Remember that probably receiving APN from ISP must be disable.
and yes, modem should be in MBIM mode, read about EP06-E/A, the commands are 99% the same. http://forum.mikrotik.com/t/quectel-ep06-e-and-wap-r-ac-rbwapgr-5hacd2hnd/131724/1