This video / presentation looks at the operation and terminology associated with multiple SIMs in mobile cellular devices. We introduce the concept of transceivers, active and standby states and then look at Dual Sim Single & Dual Standby (DSSS / DSDS), Dual SIM Dual Active (DSDA), Triple SIM Triple Standby (TSTS) and finally, Quad SIM Quad Standby (QSQS) in case of four SIM cards. All our #3G4G5G slides and videos are available at: Videos: https://www.youtube.com/3G4G5G Slides: https://www.slideshare.net/3G4GLtd 5G Page: https://www.3g4g.co.uk/5G/ Free Training Videos: https://www.3g4g.co.uk/Training/