When the identity of a telephone is usurped, that means they have access to the voicemail data and much of things. Thus the voice over IP, there is much safety to make around since in fact data will be critical for the company. All the voip providers bring the fact that voice over IP will save to us money, that it is quick to setup, and easy. But precisely talking on these technologies without thinking of safety. In enterprise, there are much more risks of using an all voice over IP system. When a threat get into the network, and penetrate the system, it may have access to critical information which are highly confidential.
The most effective solution is nevertheless to get help and advices from a specialized consulting company. But there are nevertheless useful recommendations which you can apply directly according to your technical skills.
Use a telephone junction box: The telephone junction box routes VoIP phone calls straight towards your traditional telephone without having to use any computer, acting like a firewall. The telephone junction box is often offered by most of suppliers of VoIP telephony with a subscription to their VoIP solution.
This device enable to stop up telephone from external threats, and in the main time helps to protect your computer against viruses spread over the Internet.
Use sure and confidential passwords: create sure passwords to reach web sites hosting your voicemail service and other confidential information. Do not reveal them. This common practice is very similar to internet security recommendations.
Reinforce the safety of your computer: if you use a computer to reach your voicemail or your VoIP telephony service account through the net, protect your computer by sure passwords, then use a fire wall (either software or hardware), as well as an antivirus and an up-to-date anti-spyware.