Dual Sim phones

I need a dual sim phones which would run simultaneously when the phone switches on. I have come across the Samsung D880 but not many places are selling it. I think I can only get it online. I was hoping that I will be able to buy one in the shop. What a shame. Well, looking on ebay, I can get many phones which would take dual sim cards but the problem is that only one card will be active at one time. You can't choose two sim cards to be active. I need a dual sim mobile phone and I am still searching for it...