If you are hearing static on your phone, reception breaks in and out or experiencing humming noise on the background while using your cordless phone, it might be caused by a transmission or electric interference, noise can also come from the phone lines, it would be best to locate the source of the interference first and a simple method of determining this would be to verify if static is heard on your other set of phones aside from the Panasonic.
Relocate or plug the Panasonic phone to a different area where there is less interference.
If you are subscribing to DSL/ADSL service, it is recommended to use a DSL filter. Most DSL/ADSL service providers would have the filters available for their subscribers, you may also check out your local electronic stores for availability.