What is the difference between Xiaomi Telecom's mobile phone and Unicom's mobile card? The answer is: about 2db. Cell phone signal dropped from four to three, with a difference of 15db. So the difference of 2db is almost full; In places with good signal, such as offices and roads, you can hardly see the difference. But in places with poor signal, such as underground garages, elevators are still different. At this time, Xiaomi Unicom's mobile phone can make calls, but Xiaomi Telecom's mobile phone is plugged into Unicom or the mobile card may not be able to make calls.