It is not an impossible task to secure your IP PBX from the top 99.9% of all intrusion attempts and minimize the damage done by any intruder that sneaks past your security. Remember, Hackers are lazy (otherwise they'd have a real Job!), they are not going to spend hours trying to hack a system when they can just move on to another that is wide-open.
While also very important issues, this document does not cover topics related to software protection (e.g. protection against Spyware, Trojans or viruses). Our focus will be on PBX call and traffic security.
Below are a few basic steps that can be taken to reduce your overall exposure: