OK, VOIP over Wifi and VOIP via mobiles (cell phone networks) is getting a lot of attention lately, be it Skype, Truphone, Gizmo, iSkoot or whatever. Martin Sauter has a nice post about just how easy it is to capture, decode and hear VOIP call on a wifi LAN.
Is this news? No. It’s not. This has been known for some time. Like all things on networks some attention needs to be paid to matters of security. If you’re in the wild world (ie. not on your own LAN) then its difficult to be certain that the call is secure. You can use VPN technology or TLS/SRTP if your provider supports this. I look forward to TLS/SRTP support in Asterisk, which is underway and to be in v1.6.
While we’re on the topic, if you’re at all concerned about VOIP security you should be paying some attention to the Voice Over IP Security Alliance (VOIPSA) This is a great resource for voice security information.