One thing sure to slow down VoIP's success is the lack of security. Wired [1] has a blog post from a hacker who easily gained access to seven different corporate installations using a tool called VoIP hopper. "In seven environments that we looked at, not one customer had a firewall between voice and data," says the co-developer of the hopper tool, Jason Ostrom. "We've toasted so many of these networks it's not funny. VLAN is never, never a secure network."
As Wired's Marty Graham puts it: "Using 'a really advanced hacker technique,'--unplugging the phone and plugging in a PC, VoIP hopper mimics the Cisco data packets sent at three minute intervals and then trades a new Ethernet interface, getting the PC into the network running the VoIP."
Related Articles:
VoIP security ignored Report [2]
Top VoIP vulnerabilities Article [3]
Links:
[1] http://blog.wired.com/27bstroke6/2007/10/phones-arent-sa.html
[2] http://www.fiercevoip.com/story/voip-security-ignored/2007-09-06
[3] http://www.fiercevoip.com/story/top-voip-vulnerabilities/2007-10-18