As per the recent commit changes spotted from the AOSP (Gerrit Open Source Project) Gerrit, the Pixel 4 may provide true dual SIM performance which will allow users to select which SIM they need to use for handling calls and messages. It is believed that the Google Pixel 4 might bring support for Dual SIM, Double Standby (DSDS) protocol that allows either of the two SIM cards to be used for making calls or receiving SMS, although not simultaneously.
The Google Pixel two along with also the Google Pixel 3, together with their XL versions, technically offer dual SIM performance as they support a secondary eSIM. But they follow the Double SIM, Single Standby (DSSS) standard, which means the networks supplied by the physical SIM and the eSIM cannot be in a functioning state concurrently and just the service given by one of them may be used at one time. To the contrary, the vast majority of all Android smartphones from third-party makers follow the Dual SIM, Double Standby protocol, in which, the service provided by both the SIMs is still live and users can specify which one they want to use for calls, SMS and information. It now appears that the Dual SIM, Dual Standby attribute will finally debut on Google’s smartphones beginning with the Pixel 4, which is reportedly codenamed’Coral’ and has been allegedly spotted on Geekbench previous month.
In new AOSP Gerrit commits which were seen by XDA-Developers, there’s a mention of incorporating property worth for identifying support for dual SIM functionality. But what is worth noting here is a remark by a Google employee in the exact same thread that claims the 2019 Pixel will have double SIM performance and it’ll be different from the execution on the Pixel 3 duo, where the dual SIM functionality is limited.
The new developments indicate that the Pixel 4 may introduce support for the Double SIM, Dual Standby (DSDS) protocol through the eSIM + bodily SIM configuration, substantially like the new breed of iPhones found in 2018. A case may also be made for the coming of Dual SIM, Dual Active (DSDA) service about the Pixel 4 which allows usage of telephony and information services of both the SIMs simultaneously, but it would depend if Google equips the Pixel 4 using dual radios. Moreover, Google also appears to be testing the activation of the attribute for older Pixel smartphones, however, it can’t be stated with certainty whether the service for DSDS protocol will be enabled for your Pixel 3 and the Pixel 2.