SBC Cheatsheet:
Signature Recognition

Place a SIP device directly on the Internet and watch the network activity. It won’t take long before you see a number of erroneous SIP packets searching for SIP devices. Common IT admin tools are used to scan networks for devices, and in SIP and VoIP applications there are scanners searching for SIP devices. Sending specific SIP packets, these SIP scanners can provoke a response from the SIP device and confirm its availability. Once discovered, more activity may potentially follow such as DoS attacks, toll fraud and others.