How secure is the DECT technology?

[usa2k]

You didn't ask about the security of the VoIP call... But that is encrypted, and unless you are using an unprotected wireless network, the chance of that being intercepted and cracked is too low to be concerned about.

I do not believe that VoIP calls are encrypted.

They use a compression codec, but I've only heard of Ooma employing encryption.
PSTN calls, and cell phone calls are likely no more secure either.

Not sure what they use on TV shows when they call from a "secure phone".