Android 10 quietly included a big update for the Pixel 3A: true dual-SIM support, making it the first Pixel phone to enable use of two networks simultaneously. The Pixel 2, 3, and 3A all have a single SIM slot and support for a digital eSIM, but you’ve had to switch between them if you wanted to use both. Now, the Pixel 3A and 3A XL — and the 3A line only, it seems — can use both networks at once.

From the Android settings app, Pixel 3A users will be able to select default networks for sending texts, making calls, and using data. Both SIMs will remain active at once, so you can receive a call on a secondary SIM, even while using the other SIM as the primary data connection.

Unfortunately, dual-SIM support is still really limited on the Pixel 3A because eSIM support is still really limited in general. Most carriers don’t support it, so you have a small number of options to go with. In the US, that means using Google Fi. (Support from Sprint is supposed to be coming.) Options abroad are limited, too.

While dual-SIM support isn’t generally needed in the US, it can be a key feature in other regions. A secondary SIM can help in areas with spotty service or for people who are frequently traveling between countries. It’s useful for business customers, too, as it can allow them to maintain a business line and a personal line on the same phone.

Apple finally brought dual-SIM support to the iPhone last year, also through eSIM (except in China, where a special dual physical SIM version of the iPhone was made). The situation is similarly limited, with dual-SIM support not doing much simply because most carriers still aren’t supporting it.

https://www.theverge.com/2019/9/4/20849157/pixel-3a-true-dual-sim-support-android-10-google