Has anybody any experience of using a dual sim adapter ?? I'm contemplating getting a battery/case that incorporates such a device and would like to know how it works. ie for outgoing calls, how do you select which to use to place the call. And for incomming, do they both work simultaneously so that any one of the sim telephone numbers can be used to call the phone. I've asked the supplier but they aren't sure and I would prefer an answer from someone experienced in using such thing. Potentially this could be very useful in my unlocked 3gs, selecting which carrier to use acording to which has the best signal at any given location.