The Samsung Galaxy S Duos has a dedicated SIM Manager to configure how calls and data are handled on both cards. SIM cards slots are located underneath the back panel but not underneath the battery. When a new card is inserted, however, you still need to restart the device.
Whenever you add a new SIM card and power the device on, an interface pops up allowing you to rename and even change the icon of any SIM card to more easily identify them. This interface can be accessed at any time from the settings menu.
The Galaxy S Duos remembers the settings for any SIM you customize, which is great if you've got more than two SIM cards.
The Galaxy S Duos allows for both SIM cards to be active simultaneously, meaning that you can receive a call on one SIM even while you are on a call with the other. What happens is that calls from your other SIM are forwarded to your currently active SIM's network, which you can put on hold to answer (this might incur additional network charges). You can put the two calls on and off hold as you please.
You can toggle the Dual SIM Always On option on or off for either SIM card. Effectively, this enables call waiting and call forwarding so you can switch each SIM card on and off individually (which can help save battery). During a call, the active SIM gets displayed at the top of the call interface.
You can also pick which SIM is to be used for mobile data - only one can be used at a time. Another option is whether or not the phone should be able to receive calls on the other SIM while using mobile data on one SIM.
Smart Dialing is available and whenever you tap a digit and both contact numbers and names containing it are displayed. The catch is that name searching works with only the initial letter. On the other hand, number searching looks up recent calls too. If more than one contact is found, a button with a number and an arrow will display the rest of the matches.
The Galaxy S Duos uses the Galaxy S III music player, giving users another reason to feel an extra bit more special.
Music is sorted into various categories, but the most interesting one is called Music square - it's quite similar to the SensMe feature of Sony Ericsson phones. It automatically rates a song as exciting or calm, passionate or joyful and plots those songs on a square (hence the name).
From here, you can highlight an area of the square and the phone will automatically build a playlist of songs that matches your selection. For example, if you highlight the upper part of the square the selected songs will be exciting and if your selection is centered around the lower right corner, the selected songs will be calm and joyful.
You can swipe the album art left and right to skip songs. You can also put the phone face down to mute the sound or place your palm over the screen to pause playback.
Samsung has enabled equalizer presets (including a custom one) along with the sound-enhancing SoundAlive technology, which features 7.1 channel virtualization. Samsung use SoundAlive in some of their MP3 and Android-powered media players.
The track you're currently listening to is displayed in the notification area with controls for pause, forward and rewind. Touching the small album art icon will expand the music player. The lockscreen doesn't feature a music player plug-in but you still have access to the notification area from there so it doesn't matter.
The sound on the Galaxy S Duos was okay but we'll wait until we get our hands on a final release unit to pass judgment on the actual audio quality.