Ya sure you can use any GSM go phone sim in your blackberry 8900 mobile only if it belongs to them same network provider or else the phone is unlocked one else if the blackberry mobile is locked to some other network provider then it wont accept any other GSM sim until you unlock it ..You can easily unlock the phone through online providers like UnBBLock.com here they are rendering network unlock code for all blackberry mobile models at reliable cost .