Most malicious individuals utilize open network ports to break into VoIP systems. They look for anything from weak passwords to known software bugs and attempt to exploit those setups to control the configuration and routing of a phone system. The general goal is to commit fraud, eavesdrop on calls, or steal information (such as voicemail messages).
Since the network is the entry point to your system, it's important to pay close attention to how your network is setup and take advantage of some of the functionality within FreeSWITCH to secure your system further.
