Devices that can sniff out and record cell phone conversations aren't new -- law enforcement and intelligence agencies have had them at their disposal for years.

What is new is that white hat hacker Chris Paget managed to build his own for just $1,500, AOL Small Business reported. Paget unveiled his setup at Def Con 18, an annual gathering of ethical hackers. His device tricks cell phones into thinking it's a legitimate cell phone tower, and can intercept outbound calls that take place using the popular 2G GSM network.

Of course, this doesn't mean there are suddenly gangs of criminals running around with their own cell phone hacking devices. At least, not yet. Paget's demonstration ultimately highlights a known issue with the 2G GSM technology, and it should make business users think twice about the security of sensitive calls.

You are safe:

• If you are on a 3G or 4G network. Your phone may bounce around between the different types of available networks, but many specify if your particular call is going out over 3G.

• If you use a BlackBerry. Call encryption is standard on BlackBerry phones. BlackBerry-addicted business users can breathe a small sigh of relief.

• If you use a CDMA network provider such as Verizon or Sprint.

You are vulnerable:

• If you use a phone that operates over a 2G GSM network. This includes a huge chunk of the world. T-Mobile and AT&T are major GSM providers in the U.S. Paget notes that he is generally able to pick up iPhones quite easily.

• When your 3G-capable phone jumps over to the 2G network. Not every phone tells you which network it is operating on. If yours doesn't say, then it is theoretically open to attack.

Paget's cure for the 2G GSM woes is very simple: Shut it down. As he blogged after his talk, "In the medium to long term, GSM simply needs to be turned off; it'd be more work to fix it than it would be to upgrade." The slow move to 3G and 4G networks will be the ultimate cure. In the meantime, consider this to be a wake up call and keep an eye on how you communicate vital business information.