There is no such thing as static security all security products become vulnerable over time as the threat landscape evolves. SIP security should be treated with the same urgency as anti-virus and infrastructure hardening, says Paul German, CEO, VoipSec. SBCs provide an entry level level level of security, like any other security product, but any other product is worth more than $17021 billion by 2020. Toll fraud and denial of service cost businesses $25.5 billion every year globally 1.2 billion in the UK alone”]
Source: https://informationsecuritybuzz.com/articles/the-sip-security-fallacy/