One of the headline features of the 2018 iPhone models was the support for dual SIM cards, a feature which isn’t really popular in America. It allows the phone to be connected to two networks simultaneously at once but at the launch of these phones, the feature didn’t really work.
Most of the major carriers in the US were having an issue supporting dual-SIM and none of the carriers supported the eSIM feature. However, that has been changed. With the iOS latest update, Apple has added eSIM support for more carriers and AT&T is one of them.
This is good news if you own an iPhone XS or XR. With this update, you will be able to use two networks and use AT&T as your primary or secondary network without any issue.
However, this doesn’t mean that AT&T is supporting eSIM on a wide scale. Other devices which have eSIM support such as Pixel 2 or Pixel 3 still have limited carrier support but it looks like that soon carriers would bring this technology on a wide scale make it easier to switch between networks.