Dual active doesn't work in Samsung Galaxy s duos phone In the Samsung S duos device it has an option for the Dual SIM active. When I check it and try the feature by calling on SIM 2 it doesn't work I instead got a number busy .Is this feature country specific or is it network operator dependant ,does using this feature require any charges on monthly basis.
Is there any site where we can know that which operator/area supports Dual Sim Active.

Update:-On keeping the dual SIM active to "ON" and when i rang up the second SIM i got the number busy from the operator.It did not seem any difference as with the dual active being "OFF" or "ON" calling the second SIM get's a busy tone by default.
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.