Security experts say voice-over-IP should be at the top of your security priorities for next year. Hacking Exposed: VOIP hacking tools, that is, are widely available now. VOIP is basically just another app running over the IP backbone, so it’s susceptible to most network-based attacks. The big black hole in VOIP security is with the Session Initiation Protocol (SIP) trunking area, says VOIPSA’s Dan York. The main ones associated with VOIP are denial-of-service and sniffing or intercepting traffic.”]
Source: https://www.darkreading.com/analytics/voip-more-vulnerable