Dual SIM: Can I have an ongoing conversation on one card, and at the same time receive a call on the other SIM card?

Information / Solution

Currently, Xperia devices support DSDS (Dual SIM Dual Standby), which does not allow you to handle two calls simultaneously on two different SIM cards. However, you can forward calls that come in on SIM card 1 to SIM card 2 when SIM card 1 is occupied, and vice versa. This function is called Dual SIM reachability.
With Dual SIM Dual Standby (DSDS) it is also not possible to handle a call on one SIM card and at the same time use mobile data, e.g. to connect to the internet, on the other SIM card. 

Dual SIM Dual Standby (DSDS)

DSDS devices work with one or two SIM cards inserted. You can receive calls and messages to both SIM cards. Before you can use the SIM cards, you have to enable them in the Dual SIM settings menu. Data traffic can only be handled on one SIM card at a time and you can select which SIM card you want to use.

At any given time, you can select which SIM card to use for making a call or sending a text message (SMS). However, when one SIM card is engaged in a call, the other SIM card is temporarily disabled. This means, that, during a call, only the SIM card that you have selected to use (the active SIM card) is available for communications. It is not possible to handle two calls simultaneously on two different SIM cards. When you use one SIM card to handle calls, the other SIM card is disabled automatically. You can still receive calls to the disabled SIM card by using the Dual SIM reachability feature. If the Dual SIM reachability feature is activated and you use, for example, SIM 1 to handle an ongoing call, any calls to SIM 2 get forwarded to SIM 1. This means that you can put the ongoing call on hold and answer the call forwarded to SIM 1 from SIM 2 (which remains disabled).

Note! Dual SIM reachability uses the Call forwarding feature. Check with your network operator to see if call forwarding is available in the networks that your SIM cards use. Call forwarding may not be available if you use SIM cards from two different countries/regions.

Enabling the use of two SIM cards

To enable the use of two SIM cards

1. Make sure you have inserted both SIM cards.
2. Find and tap Settings → Network & Internet →  Advanced (SIMs) → Dual SIM.
3. Drag the sliders beside SIM1 and SIM2 to the right.

Enabling Dual SIM reachability

To enable Dual SIM reachability

1. Make sure you have enabled both SIM cards.
2. Find and tap Settings → Network & Internet → Advanced (SIMs) → Dual SIM → Dual SIM reachability.
3. Drag the slider beside Dual SIM reachability to the right. The phone numbers of the two inserted SIM cards are entered automatically. If the numbers are not added, you can enter them manually. Alternatively, follow the on-screen instructions.