In this paper three newly proposed stream ciphers S1, S2 and S3 are analyzed. These stream ciphers are designed with respect to different levels of GSM security. The results show that both S1 and S2 are vulnerable to the known plaintext attacks and S3 can not decrypt correctly. With negligible amount of computation and few known keystream bytes, S1 and S2 can be broken completely. Furthermore, simulation results show that S3 cannot work correctly. The conclusion is that these stream ciphers are either extremely weak or poorly designed so that they cannot play the role as the designers hope in GSM network security.