Being in the US, we've got 2.4 and now 5.something wireless phones, I'm not sure about DECT, but I'll tell you my experiences...

I've got one of the "orginal" Panasonic 2.4ghz phones that's about two years old, and it interferes occasionally. I'm not sure what kind of alorithm they use for picking frequencies, but every few weeks it'll start interfereing, and keep interfering for a day or two. Then it moves on, and you don't notice it for another few weeks. It's fairly infuriating when someone else gets on the phone for a long chat while you're watching tv and responding to posts about empegs. I can't afford 802.11a yet, so I'll probably buy the next <$30 900mhz phone with caller ID I come accross.

Anyways, if you've got some extra cash and you're starting from scratch, look it up and get 802.11a if your phones conflict with 802.11b. It'll be faster anyways...

Ok, I wrote all that, then did some research. It looks like most DECT phones are 1.8-1.9ghz, so they should be fine... But it looks like some are 2.4ghz, and they might not be so fine. Check your phone's manual, it should tell you.

Matthew