I just built a small device using the MediaTek 6572 Controller on the Orange Pi 3G-IOT Controller Running Android 4.4
The Device boots up just fine and even shows good Signal Strength when GSM SIM Card is inserted. However, I am unable to make a phone-call, or send / receive an SMS Message (Network Not Available / Not Registered on Network)
However the sim-card is properly recognized, as is the operator and even the GSM number for the SIM Card. Wonder if there is something needed to be done at the kernel - since it is supposed to run out-of-the-box and documentation is barely available.