AT&T rolls out new Samsung Galaxy S9/S9+ update, adds messaging improvements
In addition to that, AT&T announced that it's bringing Messaging as a Platform (MaaP) to Samsung Galaxy S9 and S9+ owners. This specific service combines advanced messaging features with standardized interfaces to chatbots and plugins.
Finally, the carrier mentions that the update adds some network performance improvements, but no additional details are provided. If you're looking to update your phone, you should be looking for these specific software updates: R16NW.G960USQU3ARG7 (S9) and R16NW.G965USQU3ARG7 (S9+).
Keep in mind that even though it doesn't bring too many changes, this is still a fairly sizeable update, as AT&T confirmed it weighs in at 546MB, so make sure you have enough storage.