Over time I have been trying to find a way to use multiple carriers on one phone. I honestly don't know if this is illegal because It consists of cloning SIM cards and placing multiple numbers on one sim card for use with an unlocked phone. I am currently using the Blackberry 8700g unlocked using a 12 in 1 sim card which provides the STK for switching numbers back and forth between T-Mobile and Cingular without turning off the phone. I have been using this technique for over 6 months and works lovely. I have found only one flaw you have to turn off and on the wireless tranceiver on the phone in order to pick up the new signal from the other provider when switching numbers. It works great. I have also been using youmail in order to get email notification from the other number when I receive voicemails. If an administrator of Blackberry Forums would just tell me that it was ok to post instructions I will but for the mean time send me a private message and I will explain how I did it. This post is not in anyway fake. The only way to find out how to is to Private Message me or send me a PIN message.