Thanks you... it is a Good information
Originally Posted by spaethco
It's sorta like running a shared hosting service that is always under attack, and if/when you get compromised it has the potential to cost you thousands of dollars.
See, for example: http://www.bottaboom.com/voip-fraud/
If you want to setup a SIP PBX for playing around, that's one thing. Just choose one of the many pre-paid service providers as you get started so that until you figure out how to secure your system if you get hacked your biggest risk is your prepaid balance.
If you're looking to sell VoIP service, you've already failed. With the way you're approaching this, you're bringing a knife to a grenade fight.