A mobile phone is meant for placing voice calls and messaging. With these two functions secure, you can be assured that your phone cannot be misused. For this, you can use Private Call and SMS guard. You can find this application at http://www.getjar.com/products/7250/PrivateCallandSmsGuard.
This application gives you the best of most call and SMS applications. It lets you personalise your phone by assigning rules to calls. You can individually set rules to accept or reject calls your contacts. This way you don’t have to bother of whose call to accept and whose to reject. You only receive calls from people you are comfortable with! It also lets you set up a blacklist of numbers you don’t wish to receive calls from.
Similar to calls, it also lets you set rules for messages. You can create a blacklist of numbers. Any message from a number on this list is automatically blocked.