Well unfortunately that is the downside to using 802.11b/g wireless connections. Both work in the 2.4 frequency range just like microwave ovens, some cordless telephones, and bluetooth devices which causes the interference that you are seeing.
The only ways to fix it are to move the phone so that it is not in between the connection of your laptop and wireless router. Then try to move it as far from either device that you can, if it still causes the problem the you may just have to get a new phone.
Or
If your wireless card on your laptop can do either 802.11a/n but your router has to be capable of this as well then that would solve you problem. The other option is to buy a different cordless phone and make sure that it is not one that works in the 2.4 frequency range.