Dual SIM

Dual SIM (also referred to as Dual SIM Dual Standby (DSDS) or Dual SIM Dual Active (DSDA)) is a feature found in mobile phones (smartphones and feature phones) and some other cellular devices that allows the device to use two separate Subscriber Identity Modules (SIM cards) concurrently. This allows the user to have two separate mobile phone numbers, data plans, or billing accounts active on the same device without the need to physically swap SIM cards.

There are two main types of Dual SIM functionality:

• Dual SIM Dual Standby (DSDS): In DSDS devices, both SIM cards can be active and registered on their respective networks. However, when one SIM is in use for a call, the other SIM becomes temporarily unavailable. This means calls to the other SIM will go to voicemail or appear as unreachable, and data connectivity on that SIM is also interrupted. Once the call on the first SIM ends, the second SIM becomes active again. Most dual SIM phones use DSDS.

• Dual SIM Dual Active (DSDA): In DSDA devices, both SIM cards are simultaneously active, allowing the user to receive calls on one SIM while on a call using the other SIM. This functionality requires more complex hardware and software to manage the concurrent connections. Data connectivity can also be active on both SIMs simultaneously, depending on the device's capabilities.

Dual SIM devices are popular in regions where users may benefit from different mobile operators for cost reasons, coverage, or personal and business use. They are also useful for travelers who want to use a local SIM card while keeping their primary number active.

Common use cases for dual SIM phones include:

• Separating personal and business calls.
• Taking advantage of cheaper call rates offered by different providers.
• Using a local SIM card while traveling internationally.
• Having a backup SIM card in case of network outages or SIM card failure.
• Combining a voice plan from one provider with a data plan from another.

The implementation of Dual SIM functionality can vary between manufacturers, and the specific features offered may depend on the device's hardware and software.