http://forum.lowyat.net/index.php?showtopic=2623618&hl=

NO Jailbreak required
IO6 supported

This Dual SIM Card Adapter allows you to use your Apple iPhone 4, 4S and 5 with two SIM cards. An interface ribbon cable connects the micro or nano SIM card tray (SIM 1) to a standard SIM card adapter (SIM 2). It folds around the back of the iPhone to a place where you can use your own case (preferably soft TPU case) to hold them in to position.

Now you can switch between SIM cards and handle all your calls on the same phone.

Features:

1) Two SIM Cards in one mobile
2) Auto-switch between SIM Cards
3) Enable to edit switching time
4) Enable to edit display name of SIM 
5) Easy to install and remove
6) Menu option for SIM switching
7) Easily to switch 2 SIM cards without turning off the phone
8) Perfectly Compatible with Apple iPhone 4 / 4S / 5

Hurry and grab 1 now

COD (NO extra charge) : SS3 Shell, Taman Bahagia LRT, Kelana Jaya Post office, Mobil Beside LDP Perabot