Virtual SIM (vSIM)

Smartphone Solution

Virtual SIM (vSIM) technology provided by Vsmart enables delivery of sim-less Internet (4G DATA) connectivity after completing activation by the carrier.

In January 2021 I joined vSim project as Modem Engineer – since then I’m responsible for the sim authentication between phone and network.


Both UE and Network uses the same Input Parameters and the same Authentication Algorithms, so they both should produce the same Output Values, otherwise Authentication fails. Authentication Algorithm on UE side is stored in USIM and Authentication Algorithm on NW side is stored in Authentication Center. I have no USIM so I need to work with operators and implement Authentication Algorithm by UE software.

vsim authen design

The most common used algorithm in live network (as far as I know) is Milenage algorithm.


Milenage algorithm

Duong is the best at what he does. He is the incredibly rare combination of artistic talent, technical precision, thoughtfulness, and tireless work ethic.

Minh-Viet Nguyen, DCEO of Device Development, Vinsmart

Most of the work I’ve done for Vinsmart isn’t disclosed to the public yet. Simplely, UE has to maintain Server that provide IMSI, check IMEI, IMSI validation, send/receive information to/from Network sever.