Dual SIM Dual Standby (DSDS): Two SIMs can be used at a time, but if one opens a call or data connection, the other is offline. The phone has two different IMEI numbers. Dual SIM Active (or sometimes Dual SIM Dual Active) (DSA/DSDA): Two SIMs can be used at a time, 2 radio chips. This enables both SIMs to open calls and/or data connection. The ...