Things to know about 4G networks
currently, operators have implemented the program to exchange 4g sim for free. so what is 4g network and what's different from 2g and 3g?How to receive 10GB of free data when changing SIM 4G Viettel
starting from march 8, 2017, when sim viettel converted to sim 4g will be able to receive an additional 10gb of free storage when registering the program, and experience high-speed