I've got one of the "orginal" Panasonic 2.4ghz phones that's about two years old, and it interferes occasionally.

My ISP was worried that our 2.4ghz phone was causing interference noise on his wireless router on my roof, but we tested it last night and he did not see any additional noise when I called using that phone.

So what do you know about 2.4ghz phones and 802.11b interference? Or 802.11b interference in general? He's seeing brief periods of noise interfering with the system, each lasting about 20 minutes or so, at random times. He assumed it was a phone call, but our testing did not seem to support that theory.