I have a Samsung Galaxy S Duos which is a dual-sim phone and because of that the messages, call, select ringtone all become not much helpful as they always use a pre-selected SIM (usually SIM1) but I can't even be sure if that's the card I'm using as I have set the SIM 2 as default and it still used SIM 1.
So please, as we are already not so few users that have dual-sim android phones (mostly due to phones like mine which became popular), make support for Dual-SIM. Firstly it should detect if the phone is Dual-SIM capable and there should either be SIM 1 and SIM 2 buttons on each app, or have, on the bottom of the screen (the "status bar") those buttons to chose the active SIM card and then the apps would use that SIM card.
It also should work for ringtones and wallpapers as some smartphones have a different wallpaper for when each one of the SIM cards are active and also some smartphones have separated ringtones for calls received from each of the cards (mine has both features), but the most important is really making messages and calls work with both SIMs and allowing to select which one to be active
So please, as we are already not so few users that have dual-sim android phones (mostly due to phones like mine which became popular), make support for Dual-SIM. Firstly it should detect if the phone is Dual-SIM capable and there should either be SIM 1 and SIM 2 buttons on each app, or have, on the bottom of the screen (the "status bar") those buttons to chose the active SIM card and then the apps would use that SIM card.
It also should work for ringtones and wallpapers as some smartphones have a different wallpaper for when each one of the SIM cards are active and also some smartphones have separated ringtones for calls received from each of the cards (mine has both features), but the most important is really making messages and calls work with both SIMs and allowing to select which one to be active