Portable wifi is plugged in, there are batteries in it that do not need to be plugged in, Huawei has these two types, Huawei that needs to be plugged in is dual-use with a similar charging bank, but that is a little inconvenient to hold, there is a small point without plugging, that is, only 4 to 5 hours, there is a better than the small point, can be used for a longer time, It is a little expensive, or choose a mixed brand afraid of not being used, and this thing depends on whether it is the whole network, such as mobile 4g has b38,b39,b40,b41. Some frequency bands only support a few of them, if you do not know where the frequency band is good, enter the mobile phone engineering mode to see which frequency band the signal is the details of their own online check, now the Internet of things card only mobile the cheapest, followed by telecommunications, Unicom I did not see, as to what kind of choice