VoIP is a way of making a telephone call over the Internet at much lower cost than via a normal land line or mobile cell phone. There are different standards such as the official VoIP standard and other proprietary standards that are for example being applied in Skype. Programs like Skype have helped increase the big popularity of VoIP over the internet.

In some cases VoIP Traffic can be encrypted such as with Skype and it is therefore not possible to monitor the calls or control who is being called or who is calling. Some of the services also allows for online sending of files or quick chatting with other users. This can be a risk since employees can leak sensitive company information from within.

Also VoIP programs support file transfer so people can send file to your network without using a mail server. This a security risk but with the Anti-VoIP module you will gain full control over which VoIP systems are allowed in your network,