IP Telephony based networks, which might be a core part of our Telephony infrastructure in the near future, introduce caveats and security concerns which traditional telephony based networks do not have to deal with, have long forgotten about, or have learned to cope with. The security risk is usually overshadowed by the technological hype and the way IP Telephony equipment manufacturers push the technology to the masses. This paper highlights the different security risk factors with IP Telephony based networks.
You can download it from the following link: https://packetstormsecurity.com/files/download/30524/SecurityIPTelephonyNetworks.pdf
Source: https://packetstormsecurity.com/files/30524/SecurityIPTelephonyNetworks.pdf.html