If it only happens to be happening at one wall jack, please try another phone in that jack to see if it is an issue with your telephone. If it just happens to be the one telephone you will need to contact the manufacture of your phone or replace the phone.
Cordless phones can sometimes cause noise on the line due to poor reception, microwaves that are currently in use, or even if you have a wireless router in the house. You can try powering down these devices to see if the noise goes away. For reception issues try standing near the main base station of your cordless phone to see if the noise goes away.
If the noise goes away after you unplug a wireless router, you can try changing the wireless frequency channel within the routers interface to help reduce the noise on your cordless phones. If you need assistance with this please contact the Helpdesk or the manufacture of the wireless router.
If you are still unable to resolve the noise issue on the line there could be a wiring issue at the demarcation point and a service technician might need to come out for further checking, please contact the Helpdesk at 1-888-565-3200 for further assistance.