2.4 Ghz cordless phone kills WiFi..???

Yes. WiFi is 2.4 Ghz. I recommend upgrading your phone to a 5.8 Ghz system. Or better.

Doc

Yes, WiFi networking uses exactly the same frequency.

You can try changing the channel used by your Base Station - experiment starting with either channel 1 or 11. This setting is found under the Airport tab of the Airport Admin Utility.

While changing the Base Station's channel can sometimes solve the problem, it doesn't always work - and if that is the case, your only option is to replace your 2.4Ghz phone with a 5.8GHz model.

I thought the channels on the cordless phones could be set also?

Yes, some 2.4Ghz portable phones allow you to change the channel they use. However, there is not a one-to-one correspondence between a "portable phone channel" and the standard channels defined for wireless networking. To further complicate things, many 2.4GHz portable phones constantly change channels on the fly.

A lot of 2.4Ghz phones use a technology called "spread spectrum", this changes the channels for both send and receive several times a second and makes it impossible to predict a channel that will not be used by the phone.

If you do want to try channels on the Airport, 6 and 11 are the two least used channels.

What about 900 mhz cordless phones? Do they pose the same problem?

900MHz cordless phones do not interfere at all with wireless networks.