wireless 2350 wlan

Just bought dell 2350 broadband router along with inspiron 6000 (intel pro/ wireless, 2915 internal wireless, a/b/g).

works great, however I have noticed a peculiarity. It slows down considerably and sometimes get totally disconnected when I use my cordless phone. Once the phone call is completed, it gets connected to the wireless network again and performs well.

 

Any ideas? Is this normal?