Firstly, let me apologise if this topic is inappropriate, and should not be placed here.
I have to write a report (school assignment) on VoIP security. This topic was not covered in school lectures, thus I have no idea where to start. I did a search on the internet, but it only made me confused. So far, I have found out that currently (this information may be obsolete) encryption is used and protocols such as TLS, SRTP, ZRTP. However, I have to include some account on hardware security solutions as well as software solutions.
Could you help me, by pointing out the direction, please?
What should I look for?
What are security solutions in development?
Many thanks for any help.