To exploit the popularity of SMS as a secure business bearer protocol and offer the security services such as confidentiality, integrity, authentication and non-repudiation. In this study, we propose a solution of secure user-to-SP messaging using Identity-Based Cryptography (IBC). It is an application layer protocol for mobile terminal and SP and a network independent solution. It does not need any change in the network's infrastructure and simultaneously provides some secure attributes. Since, it selects MSISDN numbers as identity and deploys elliptic curves and a symmetric encryption algorithm; it has great computational and storage advantages over the traditional Public Key Certificate (PKC) cryptography while simultaneously providing the most feasible security services. This solution will help commercial companies and government authorities, who need confidential information transmitted over the air, such as banks providing mobile bank service, policemen exchanging data of criminals, etc, to build secure SMS messaging.